IGE  &  METHODS 
O^ANALYSIS  of 
IRON  AND  STEEL 


COPYRIGHT 

1ERICAN   ROLLIN3   MIUU  CO. 
MIDDLETOWN,   OHIO 
1920 


PRESS   OF 

THE   GIBSON    8c    PERIN    CO. 
CINCINNATI,    OHIO 


Research  and  Methods  of  Analysis 


IRON  AND  STEEL 


at 


ARMCO 


Second  Edition 
Price  $4.00 


THE  AMERICAN  ROLLING  MILL  COMPANY 

MIDDLETOWN,  OHIO 

1920 


Preface  to 
Second  Edition 


T 


HE  first  edition  of  tKis  book  appeared  in  1912.  The 
supply  xtfas  soon  exhausted,  and  continued  de- 
mands hav^e  made  it  seem  desirable  to  issue  a 
second  edition. 

The  methods  described  are  particularly  adapted 
to  the  analysis  of  "Armco"  products. 

Where  -well-known  methods  have  been  de- 
scribed, \tfe  have  omitted  details  -which  are  -well 
understood  by  the  skilled  chemist.  Where  new" 
methods  are  described,  we  have  entered  into 
minute  details. 

The  second  edition  has  been  entirely  rewritten, 
many  methods  have  been  added,  and  the  entire 
scope  amplified  by  the  addition  of  new  material. 


ARMCO  RESEARCH 
MIDDLETOWN,  OHIO 
1920 


444055 


I  a 

«   cti 

bfljy 

' 


It 

II 

si 

ed 


.2  £ 

JH   O 

O    OJ 

II 


J 

cu 
o 


INTRODUCTION 

iVER  since  its  inception,  The  American  Rolling 
Mill  Company  has  been  a  leader  in  the  adapta- 
tion of  science  to  practical  problems  of  steel 
making. 

The  company  was  organized  to  manufacture 
special  grades  of  sheet  metal  suited  to  the  needs  of  exacting 
users. 

A  well-equipped  research  laboratory  was,  therefore, 
essential  to  the  carrying  out  of  its  manufacturing  program. 

In  the  establishment  of  such  a  laboratory,  a  new  era 
was  begun  covering  the  manufacture  of  high  grade  iron  and 
steel  sheets  and  other  metal  products. 

In  1903  the  development  of  various  grades  of  electrical 
sheets  for  transformers,  motors,  generators,  etc.,  was  begun. 
Most  satisfactory  results  were  secured  and  research  work 
on  this  most  important  line  of  manufacture  has  been  con- 
tinued up  to  the  present  date. 

In  1908  for  the  first  time  in  metallurgical  history  and 
contrary  to  established  theories  as  laid  down  in  authorita- 
tive metallurgical  text  books  of  the  day,  a  commercially 
pure  iron  made  in  a  modern  open  hearth  furnace  was  pro- 
duced. 

This  new  metal  was  soon  found  to  be  superior  to  Bes- 
semer and  Open  Hearth  Steel,  in  the  essential  properties 
of  Purity,  Rust-Resistance,  Welding,  Conductivity,  and 
Enameling.  Its  metallurgical  and  practical  development 
is  unquestionably  largely  responsible  for  the  improvement 
made  to  date  in  the  rust-resisting  qualities  of  the  various 
grades  of  iron  and  steel  sheets  now  being  manufactured. 

In  the  early  days,  Chemistry  had  not  in  a  majority  of 
cases  been  applied  to  practical  steel  making  beyond  the 
determination  of  the  elements  known  as  "The  Big  Five" 
(Sulphur,  Phosphorus,  Carbon,  Manganese,  and  Silicon). 
Today  through  research  development,  it  is  known  that 


INTRODUCTION 


INTRODUCTION  7 

gases  such  as  Nitrogen  and  Hydrogen  are  elements  to  be 
considered  in  rust-resistance  and  other  qualities  of  iron  and 
steel. 

A  close  study  of  protective  coatings  is  another  branch  of 
metallurgical  research.  Work  along  this  line  has  been  done 
to  show  the  effect  of  impurities  in  the  coating.  It  is  a 
recognized  fact  that  pure  galvanized  coatings  are  much 
more  resistant  to  the  elements  of  corrosion  than  are  impure 
coatings,  and  experiments  are  being  constantly  carried  on 
to  further  improve  the  quality  and  character  of  these 
coatings. 

Degasification  of  metal  was  not  thought  of  a  few  years 
ago  and  yet  today  it  is  considered  of  very  great  importance. 
A  modern  research  laboratory  can  now  determine  the  gases 
in  the  metal,  and  writh  this  information,  it  is  possible  to 
maintain  control  of  the  gas  content  in  the  manufacture  of 
the  product.  The  Research  Department  of  The  American 
Rolling  Mill  Company  was  the  first  to  make  practicable, 
various  methods  for  gas  determination  in  Iron  and  Steel. 

New  uses  for  pure  iron  and  other  special  sheet  metal 
products  require  a  constant  expansion  of  research  work, 
covering  such  lines  as  vitreous  enameling,  japanning,  weld- 
ing, heat  treatment,  forging,  and  casting,  all  of  which  offer 
wonderful  fields  of  usefulness  for  the  chemist  and  metal- 
lurgist. 

During  the  last  ten  years  many  grades  of  high  polished 
sheets  have  been  produced  for  the  use  of  the  automobile, 
furniture  and  other  products.  These  sheets  must  not  only 
have  a  very  high  finished  surface,  free  from  defects  of 
every  kind,  but  they  must  stand  all  sorts  of  drawing  and 
spinning  operations  unknown  to  the  maker  and  user  of 
sheet  metal  just  a  few  years  ago. 

The  modern  research  laboratory  has  been  largely  re- 
sponsible for  all  of  these  developments  and  it  needs  no 
prophet  to  foresee  that  many  new  alloys  and  other  products, 
the  result  of  special  manufacture  and  treatment,  will  be 
developed  from  time  to  time  to  meet  the  exacting  demands 
of  industrial  progress. 


INTRODUCTION 


The  Iron  Pillar  at  Delhi,  India 


INTRODUCTION 


IRON  PILLAR  OF  DELHI,  INDIA, 
1600  YEARS  OLD 

Described  by  Sir  Robert  Hadfield 
In  the  1912  Journal  of  the  Iron 
and  Steel  Institute.  He  shows  It 
to  be  pure  Iron  of  the  following 
analysis; 

Silicon  .046 

Sulphur  .006 

Phosphorus     .114 
Carbon  .080 

Manganese      nil 
Copper,  Etc.    .034 
Iron  99.720 


10 


INTRODUCTION 


In  the  study  of  corrosion  problems  it  has  been  necessary  to  provide  extensive  proving 
grounds.       This  view  shows  one  of  the  proving  grounds 
where  various  metals  are  exposed  to  at- 
mospheric conditions 


ANCIENT  IRONS  AND  MODERN  RESEARCH 

|N  the  British  Museum  and  elsewhere  are  many 
interesting  specimens  of  age  old  irons  that  have 
resisted  the  "rust  of  time".  Some  of  them  have 
been  taken  from  the  tombs  in  the  pyramids  of 
Egypt.  Their  existence  spans  a  period  of  4000 
years  to  the  modern  world  in  which  steel  and 
iron  plays  so  large  a  part. 

For  years,  scientists  have  been  seeking  the  secret  of 
rust-resistance  of  iron  and  steel.  They  have  analyzed  such 
ancient  irons  as  came  to  light  for  a  complete  understanding 
of  their  contents,  they  have  studied  their  grain  structure 
with  the  microscope,  they  have  determined  the  gas  content, 
and  have  taken  into  consideration  the  primitive  methods 
of  manufacture  as  compared  with  those  of  today.  Out  of 
all  this  has  come  the  deductions  of  modern  science,  that  is 
marking  the  pathway  of  progress. 

The  American  Rolling  Mill  Company  has  been  an 
earnest  investigator  of  the  causes  of  corrosion.  In  the 
Research  Department  at  Middletown  is  a  museum  of  old 
and  interesting  nails  and  odd  bits  of  old  iron.  The  history 
together  with  the  physical  and  microscopical  analysis  of 
each  is  carefully  investigated  and  recorded  in  the  archives, 
while  the  specimens  are  laid  away  under  glass  cases  to  awe 
the  visitor  with  their  antiquity.  In  fact,  no  sooner  does 
an  interesting  example  of  the  old  iron  come  to  light,  than 
someone  will  suggest  sending  it  to  the  Research  Depart- 
ment of  The  American  Rolling  Mill  Company  at  Middle- 
town,  Ohio,  for  analysis.  The  study  and  analysis  of  these 
old  irons  has  brought  world  wide  recognition  of  Armco 
research  work. 

Among  the  interesting  old  iron  curios  that  have  been 
sent  to  Middletown  for  analysis  is  a  piece  of  iron  cut  from 
the  "Merrimac,"  after  having  been  in  the  water  for  more 
than  one-half  a  century.  It  is  historically  interesting  be- 
cause of  the  famous  "Monitor  and  Merrimac"  fight  in 
Hampton  Roads  during  the  Civil  War. 

11 


MCIENViRQNS  AND  MODERN  RESEARCH 


HAND  FORGED  NAIL  145  YEARS  OLD 

MADE  BY  INDIANS  AND  USED 

IN    MISSION 


ANALYSIS 


Sulphur 

Phosphorus 

Carbon 

Manganese 

Copper 

Silicon 

Oxygen 

Nitrogen 


.005 

.057 

.015 

.015 

trace 

.048 

.109 

.006 


MISSION  SAN  JUAN  CAPISTRANO,  CALIFORNIA, 
BEFORE  THE  EARTHQUAKE  OF  1812 
THE  FIRST  FOUNDING  OF  THIS 
MISSION  TOOK  PLACE 
Oct.  30,  1775. 


ANCIENT  IRONS  AND  MODERN  RESEARCH  13 

Along  side  this  is  a  collection  of  nails  from  the  Wayside 
Inn  at  Sudbury,  Mass.  Nails  from  the  famous  Fairbanks 
homestead  at  Dedham,  Mass.,  share  their  interest  with 
nails  from  historic  old  missions  of  California.  Coffin  nails 
buried  100  years  ago  and  still  in  a  state  of  perfect  preserva- 
tion have  their  own  story  to  tell. 

In  the  corner  of  the  room  is  still  another  notable  ex- 
ample of  rust-resisting  iron — the  old  iron  links  taken  from 
the  Newburyport  bridge  at  Newburyport,  Mass.  Not- 
withstanding the  fog  and  dampness  of  the  New  England 
seacoast,  when  the  bridge  was  taken  down  in  1910,  after 
100  years  service,  the  heavy  "iron  links  were  apparently  as 
good  as  the  day  they  were  installed. 

The  collection  of  interesting  specimens  is  being  added 
to  every  day.  Recently  an  old  iron  nail  was  sent  to  the 
Research  Department  of  The  American  Rolling  Mill  Com- 
pany, which  was  picked  up  out  of  the  shell-torn  ruins  of 
the  home  of  John  Calvin,  the  great  Reformist,  at  Noyon, 
France.  The  house  was  known  to  be  at  least  400  years  old 
and  yet  the  huge  iron  nail  used  in  its  construction  showed 
no  sign  of  corrosion. 

The  Research  department  at  Armco  also  prizes  most 
highly  specimens  in  its  possession  which  were  taken  from 
the  Pillar  of  Delhi,  India — the  most  notable  example  of  old 
iron  in  the  world  today.  This  wonderful  relic  of  worship 
dates  back  sixteen  hundred  years,  and  still  stands  today 
defying  the  elements  and  the  "kisses"  of  worshipers,  with 
no  sign  of  disintegration  by  rust  or  corrosion. 

Over  these  specimens  of  old  iron,  the  scientist  wrorks 
like  the  etymologist  over  his  insects,  searching  for  hidden 
secrets. 


14 


ANCIENT  IRONS  AND  MODERN  RESEARCH 


IRON  BAND  TAKEN  FROM  A  CANNON 

CAPTURED  FROM  THE  BRITISH  IN 

THE  BATTLE  OF  TICONDAROGA. 

1775-1777 
TEST  NO.  1036          FILE  51 

ANALYSIS 

Sulphur  .005 

Phosphorus  .069 

Carbon  .010 

Manganese  .010 

Copper  .080 

Silicon  trace 

Oxygen  .063 


RESEARCH  ON  CORROSION 

jURING  the  past  few  years  a  number  of  papers  have  been 
published  by  various  investigators  both  in  America  and 
Europe,  presenting  the  results  of  corrosion  tests  made 
under  varying  conditions  of  exposure,  both  in  the  labora- 
tory  and    in  the  field.     The  size  of  the  test  pieces  in 
the  hands  of  the  separate  investigators  have  ranged  from 
small  specimens  which  could   be  weighed   on  a  chemical  balance  up 
to  full  size  commercial  sheets  exposed  to   the   natural   wet  and   dry 
conditions  of  the  outdoor  atmosphere. 

Total  and  partial  immersion  tests  in  various  media,  with  loss 
of  weight  during  progressive  corrosion,  have  been  carefully  recorded 
and  plotted  in  the  form  of  curves,  and  on  these  data  in  some  cases  very 
sweeping  conclusions  have  been  drawn.  Nearly  all  the  investigators 
have  interested  themselves  in  the  possible  beneficial  or  deleterious 
effect  of  more  or  less  minute  quantities  of  some  special  impurity  or 
element,  or  in  some  grouping  or  variable  combination  of  the  usual 
constituents  of  commercial  metals. 

Thus  far  all  the  experimenters  have  contended  themselves  with 
a  discussion  of  the  possible  effect  of  solid  constituents,  without  taking 
into  account  the  possible  effect  of  impurities  of  a  gaseous  nature, 
which  are  always  more  or  less  associated  with  iron  and  steel,  such  as 
carbon  monoxide,  carbon  dioxide,  oxygen,  hydrogen,  and  nitrogen. 

It  is  self  evident  that  the  corrosion  of  iron  and  steel  depends  very 
largely  upon  the  amount  and  character  of  surface  exposed.  It  is 
obvious  that  metal  rolled  from  spongy  and  porous  steel,  some  of  the 
blowholes  in  which  extend  to  the  surface,  will  be  more  susceptible  to 
the  action  of  water  and  oxygen,  and  also  the  nature  of  such  rust  will 
be  different  from  that  produced  on  sound  metal.  As  unsound  metal 
corrodes,  a  loose  rust  is  produced  on  account  of  the  tendency  of  the 
occluded  gases  to  escape.  A  dense,  sound  metal,  on  the  other  hand, 
will  form  a  dense,  closely  adherent  rust,  and  the  rate  of  progressive 
corrosion  will  be  very  materially  reduced. 

The  fact  is  not  generally  enough  understood,  that  gases  such  as 
nitrogen,  hydrogen,  oxygen,  and  carbon  monoxide  may  be  associated 
with  iron  and  steel  in  three  separate  and  distinct  ways.  Gas  may  be 
present  as  an  atmosphere  enclosed  in  open  blowholes,  pipes  or  seams, 

15 


16 


RESEARCH  ON  CORROSION 


Section  through  center  of  Steel  Ingot, 
showing  subcutaneous  and  deep  seated 
blowholes. 


Section  through  center  of  "Armco" 
Ingot  Iron,  ingot,  shoAving  comparative 
freedom  from  blowholes. 


RESEARCH  ON  CORROSION  17 

which  may  be  large  enough  to  see  with  the  naked  eye  or  so  small  as 
to  require  a  microscope  to  resolve  them.  Again,  free  gas  may  be 
occluded  among  the  grains  or  molecules  of  the  iron,  and  be  present 
in  quantity  even  though  no  microscope  is  capable  of  discovering  its 
presence.  Finally,  gases  may  be  present  in  chemical  combination 
with  iron  or  manganese,  or  some  other  constituent,  to  form  either 
dissolved  or  segregated  nitrides,  hydrides,  oxides,  or  carbonyl  com- 
pounds. 

That  all  three  forms  of  gas  inclusions  affect  the  resistance  of  all 
metals  to  corrosion,  there  are  strong  apriori  reasons  for  believing,  even 
if  there  was  no  evidence  as  to  fact  in  support  of  such  a  view. 

We  have  sawed  ingots  of  iron  and  steel  in  two  longitudinally, 
so  that  the  soundness  could  be  observed.  The  photographic  cross 
sections  of  these  experimental  ingots  are  given. 

The  atmospheric  exposure  tests  which  we  are  conducting,  con- 
taining more  than  six  hundred  full  size  corrugated,  26-gauge  sheets, 
first  began  to  exhibit  failures  after  about  13  months,  exposure.  The 
Bessemer  Steel  sheets  have  all  failed  in  periods  ranging  from  13  to 
34  months. 

We  have  now  to  consider  why  it  is  that  Bessemer  steels  as  a 
general  rule  rust  more  quickly  than  open  hearth  steels.  As  far  as 
we  are  aware,  no  explanation  of  this  frequently  observed  phenomenon 
has  heretofore  been  advanced.  Bessemer  steel  is  made  in  America 
exclusively  in  acid  lined  converters,  and,  as  this  lining  has  no  de- 
phosphorizing action,  American  Bessemer  Steels  usually  run  a  little 
higher  in  phosphorus  than  the  general  run  of  basic  open  hearth  steels. 
This  is  not,  however,  always  true,  and  an  analysis  of  a  steel  for  its 
phosphorus  content  is  by  no  means  a  definite  proof  of  its  method  of 
manufacture.  However,  supposing  that  the  general  run  of  Bessemer 
steels  made  in  America  run  somewhat  higher  in  phosphorus  than  the 
general  run  of  open  hearth,  is  there  any  evidence  that  slightly  higher 
phosphorus  would  account  for  any  difference  in  corrosion  resistance 
of  the  two  types?  As  a  matter  of  fact,  phosphorus  is  one  element 
of  impurity  in  steel  that  has  not  at  some  time  or  another  been  held 
to  be  a  prime  factor  in  rapid  corrosion. 

It  seems  to  be  very  well  assured  that  the  tendency  towards  rapid 
corrosion,  noted  in  the  case  of  most  Bessemer  steels,  must  be  due  to 
some  element  of  difference  beside  the  usual  slightly  higher  phosphorus 
content. 


18  RESEARCH  ON  CORROSION 


IRON  NAILS  ABOUT  281  YEARS  OLD 
TAKEN  FROM  FAIR  BANK'S  HOUSE. 

DEDHAM,  MASS. 
TEST  NO.  4541       FILE  1O3 

ANALYSIS 

Sulphur  .OO9 

Phosphorus  .005 

Carbon  .015 

Manganese  .020 

Copper  .01 6 

Silicon  .029 

Oxygen  .060 

Nitrogen  .005 

Iron  99.841 


RESEARCH  ON  CORROSION  19 

Going  back  to  the  differences  in  method  of  manufacture  of  Bess- 
emer and  open  hearth  metal,  it  at  once  occurs  to  us  that  the  former 
type  has  blown  through  it,  while  it  is  molten  and  in  the  process  of 
conversion,  enormous  quantities  of  air,  more  or  less  laden  with  mois- 
ture and  gases.  Of  the  two  types  of  metal,  therefore,  Bessemer 
should  be  more  prone  to  run  a  high  gas  content  in  the  cooled  and 
finished  product  than  properly  made  open  hearth  steel.  If  this  is  true, 
the  questions  that  at  once  arise  are,  can  gas  content  be  a  factor  in 
the  relative  corrosion  resistance  of  Bessemer  and  open  hearth  metals, 
and  further  than  this,  is  the  self  same  factor  an  important  one  in 
considering  relative  corrosion  resistance  of  different  types  of  basic 
open  hearth  metal. 

Fortunately,  there  is  some  recent  scientific  data  of  a  most  in- 
teresting nature,  which  shows  in  a  most  conclusive  manner  what  an 
enormous  quantity  of  gases  associate  themselves  with  some  types 
of  commercial  steel  and  modify  or  qualify  their  physical  characteristics. 

In  1914,  L.  Baraduc  Miller  published  in  full  in  the  Carnegie 
Scholarship  Memoirs  of  the  British  Iron  &  Steel  Institute  a  report 
of  progress  on  the  study  of  gases  occluded  in  liquid  steel.  The  steel 
which  was  made  by  the  basic  Bessemer  process  was  cast  into  1000  Ib. 
ingots  and  allowed  to  cool  in  a  vacuum,  while  other  ingots  from  the 
same  heat  wrere  cooled  under  atmospheric  pressure  in  the  usual  manner 
generally  practiced  in  metallurgical  operations. 

One  ingot  of  the  vacuum  treated  steel  yields  1159.8  liters  of  gas 
measured  at  atmospheric  temperature  and  pressure.  This  gas  on 
analysis  was  found  to  have  the  chemical  and  volume  composition 
as  shown  in  the  following  table: 


Per  Gross 
Volume 

Per  Cent 

Per  Ton 
of  Steel 

Carbon  Dioxide  

Litres 
42.2 

3.6 

Litres 
76.7 

Oxygen 

10  6 

0  9 

19  3 

Carbon  Monoxide 

352  2 

30  5 

640  3 

Hydrogen  . 

604.3 

52.2 

1098.7 

Methane  

2.4 

0.2 

4.3 

Nitrogen  

...       147.7 

12.7 

268.5 

This  table  shows  the  astonishing  fact  that  more  than  2100  liters 
of  gas,  or  about  75  cubic  feet  per  ton  of  steel  was  liberated  from  the 
vacuum  treated  metal.  It  is  also  shown  that  the  principal  gases, 
hydrogen,  carbon  monoxide  and  nitrogen,  play  an  important  role  in 


20 


RESEARCH  ON  CORROSION 


MiCROSTRUCTURE  OF  LONGITUDINAL  SECTION 


IRON  CHISEL  OF  ANCIENT  ORIGIN 
ABOUT  1400  YEARS  OLD 

Described  by  Sir  Robert  Hadfieid  in  the  1912 
"Journal  of  The  Iron  and  Steel  Institute." 


RESEARCH  ON  CORROSION 


21 


the  metallurgy  of  steel.  In  another  table  Baraduc  Miller  gives  the 
following  data  to  show  the  physical  character  of  the  vacuum  treated 
steel  compared  with  metal  from  the  same  ladle  poured  and  cooled 
in  the  usual  manner: 


Test  piece  of  metal 

not  treated  for 

gases,  taken  from 

Y±  of  the  90x90 

Mms.  bars.  Normal 

cooling  and  no  heat 

treatment 


Test  piece  of  metal 

treated  for  gases 
taken  from  a  rolled 
round  25  millimeters 
in  diameter.     Nor- 
mal cooling  and  no 
heat  treatment 


Breaking  Strain  
Elastic  Limit 

40.5  Tons 
27  0  Tons 

44.  76  Tons 
35  5  Tons 

Elongation  Per  Cent 

28.9  Tons 

24  4  Tons 

Hardness 

112 

124 

Resilience  

17] 
31  \  Fibrous 

29] 
36  \  Fibrous 

Average  

19  |  Fracture 

25  J 

23 

34  1  Fracture 

34  j 

33.2 

Here  we  see  the  ultimate  strength,  elastic  limit,  harndess  (density), 
and  resistance  to  fibrous  fracture  all  materially  improved  in  the  self 
same  metal  by  the  simple  elimination  of  occluded  gases.  The  ques- 
tion as  to  whether  resistance  to  corrosion  is  also  improved  is  not 
considered. 

Baraduc  Miller  recognizes  the  fact  that  the  large  volume  of 
hydrogen  eliminated  was  furnished  by  the  decomposition  of  the 
moisture  of  the  air  used  in  blowing,  during  the  conversion.  To  what 
extent  this  is  a  factor  in  the  manufacture  of  open  hearth  steel,  is 
uncertain,  but  that  it  is  an  ever  present  factor  in  the  case  of  Bessemer 
steels,  there  can  be  no  doubt.  Baraduc  Miller  includes  the  following 
interesting  discussion  of  the  hydrogen  content : 

"In  the  case  of  hydrogen,  it  is  seen  that  the  5150  cubic  meters 
of  air  injected  into  the  converter  contained,  owing  to  the  5.672 
grammes  of  water  per  cubic  meter,  29,210.8  grammes  of  water 
capable  of  yielding,  by  complete  dissociation,  3245.6  grammes 
of  hydrogen,  corresponding,  at  about  15  and  under  a  pressure 
of  760  millimeters,  with  a  volume  of  36,058.6  liters. 

Now  with  1098.7  liters  of  hydrogen  given  per  ton  of  steel, 
measured  at  the  ordinary  temperature,  the  entire  cast  must 
have  contained,  at  a  given  moment,  13,860.3  liters  of  hydrogen. 
It  results,  therefore,  that  the  maximum  amount  of  hydrogen 


22 


RESEARCH  ON  CORROSION 


M1CROSTRUCTURE  OF  TRANSVERSE  SECTION 


IRON  NAILS  OF  ANCIENT  ORIGIN 
ABOUT  1400  YEARS  OLD 

Described  by  Sir  Robert  Hadfield  in  the  1912 
"Journal  of  The  Iron  and  Steel  Institute/' 


RESEARCH  ON  CORROSION  23 

fixed,  at  any  rate  momentarily,  by  the  steel  in  some  form  or 
other,  dissolved  or  in  combination,  must  have  been 

13,860.5  x  100_ 

-38.5  per  cent 


of  the  total  volume  of  the  available  hydrogen. 

This  throws  an  interesting  insight  into  the  extreme  solubility 
of  the  gases,  and  in  particular  of  the  hydrogen,  in  liquid  steel  at 
a  high  temperature.  It  remains  to  ascertain  if  these  gases  are 
actually  in  solution  or  in  combination,  and  also  what  is  left  of 
these  gases  in  the  steels  at  the  moment  of  solidification  in  the 
ordinary  conditions  of  manufacture." 

The  last  sentence  of  this  interesting  quotation  contains  really 
the  gist  of  the  whole  matter  and  applies  quite  as  much  to  the  question 
of  nitrogen  as  to  hydrogen.  It  has  been  pointed  out  in  an  earlier 
paragraph  that  gases  may  be  held  in  steel  either  in  a  state  of  chemical 
combination  or  merely  dissolved  or  occluded. 

Up  to  the  present  stage  of  progress  of  our  studies  of  the  effect  of 
gaseous  impurities  on  the  corrosion  resistance  of  iron  and  steel,  all 
the  evidence  so  far  in  hand  seems  to  point  to  nitrogen  as  a  more  im- 
portant factor  in  respect  to  corrosion  problems  than  the  other  gases 
under  consideration.  A  vast  number  of  analyses  of  all  types  of  iron 
and  steel  have  shown  very  significant  differences  in  nitrogen  content 
when  taken  in  connection  with  the  known  behavior  of  certain  metals 
under  test  and  service. 

In  the  discussion  of  the  possible  effect  of  nitrogen  on  the  corro- 
sion of  metal,  it  must  be  borne  in  mind  that  the  method  used  deter- 
mines only  the  fixed  or  nitride  nitrogen  that  is  present,  and  tells  us 
nothing  about  occluded  or  dissolved  nitrogen.  It  must  be  under- 
stood, therefore,  that  such  data  as  is  here  presented  has  to  do  only 
with  the  nitrogen  which  is  held  in  the  steel  in  combination  as  nitride. 

Pure  iron  nitride  has  the  theoretical  composition  Fe2N,  con- 
taining 11.8  per  cent  nitrogen.  Commercial  irons  and  steels  as  re- 
ported by  a  number  of  authorities  and  confirmed  by  numberless 
analyses  which  we  have  made,  vary  in  nitride  nitrogen  content  from 
traces  in  well  made  open  hearth  metals  up  to  approximately  .050 
per  cent  in  some  Bessemer  steels. 

Although  there  is  an  abundant  literature  on  the  effect  of  gases 
and  particularly  nitrogen,  on  steel,  there  is  very  little  evidence  in 
regard  to  the  quantity  of  free  gas  occluded  in  different  types  of  metal. 


24 


RESEARCH  ON  CORROSION 


MfCROSTRUGTURE  OF  TRANSVERSE  SECTION 


IRON  BILLHOOK  OF  ANCIENT  ORIGIN 
ABOUT  1400  YEARS  OLD 

Described  by  Sir  Robert  Hadfield  in  the  1912 
^Journal  of  The  Iron  and  Steel  Institute." 


RESEARCH  ON  CORROSION  25 

Austin  electrically  melted  a  number  of  samples  of  steel  in  a  vacuum, 
collected  and  analyzed  the  evolved  gas.  One  sample  of  mild  open 
hearth  yielded  about  one  cubic  centimeter  of  gas  per  gram,  equal  to 
about  35  cubic  feet  per  ton  of  metal.  The  gas  in  Austin's  experi- 
ments was  pumped  out  in  three  stages,  each  of  one  half  hour's  dura- 
tion. The  electric  current  was  first  adjusted  to  raise  the  temperature 
of  the  test  bar  enclosed  in  a  water  cooled  steel  vacuum  chamber  to 
900°C.  The  temperature  was  next  increased  toabo  ut  1100°C,  and 
finally  in  the  third  stage  the  bar  was  melted.  The  first  extracts  of 
gas  from  the  mild  open  hearth  steel  analyzed  as  follows: 

Per  Cent 

Carbon  Dioxide 7.7 

Carbon  Monoxide 18. 4 

Hydrogen 59. 1 

Nitrogen 14.  8 

Two  other  analyses  of  gas  evolved  during  the  last  stage  in  the 
heating  yielded : 

I  II 

Per  Cent  Per  Cent 

Carbon  Dioxide 1.4 1.5 

Carbon  Monoxide 65.  7 59. 4 

Hydrogen  and  Nitrogen.. .  32. 9 39. 5 

The  analysis  of  the  open  hearth  steel  given  by  Austin  is: 

Carbon 09 

Silicon 05 

Phosphorus 05 

Sulphur 05 

Manganese .75 

Another  medium  steel  which  evolved  an  even  greater  quantity 
of  gas  (1.35  cc.  per  gram)  had  the  analysis: 

Carbon 49 

Silicon 35 

Phosphorus 02 

Sulphur 02 

Manganese 72 

It  is  interesting  to  compare  these  results  with  those  obtained 
by  Baraduc  Miller  who,  as  described  above,  cooled  basic  Bessemer 
Steel  in  a  vacuum. 


26 


RESEARCH  ON  CORROSION 


op  to 
SS 


O  00 


en 


a  3* 

Hi 


RESEARCH  ON  CORROSION  27 

Baraduc  Miller  obtained  75  cubic  feet  of  gas  per  ton  of  metal, 
while  Austin  obtained  in  the  case  of  the  open  hearth  steel  35  cubic 
feet  per  ton.  In  the  first  case,  however,  it  is  presumable  that  some 
part  of  the  gas  collected  would  have  escaped  into  the  air,  had  it  been 
allowed  to  cool  in  a  normal  manner. 

In  Austin's  work,  however,  he  started  with  a  finished  bar  of 
cold  steel,  and  it  is  difficult  to  escape  the  conclusion  that  all  the  gas 
evolved  was  actually  held  in  some  form  or  another  in  the  body  of  the 
metal.  That  the  gas  was  present  in  blowholes,  is  impossible,  when 
we  consider  the  volume  relations  which  follow  from  Austin's  experi- 
ments. Austin  collected  gas  which,  calculated  to  a  tonnage  basis, 
amounted,  as  has  been  shown,  to  about  35  cubic  feet  per  ton  of  metal. 
Now,  since  a  cubic  foot  of  steel  weight  480  Ibs.,  there  must  have  been 
a  volume  of  gas  present  equal  to  approximately  7.5  cubic  feet  to  each 
cubic  foot  of  metal.  This  is  a  most  extraordinary  conclusion  and  one 
that  will  perhaps  be  unwelcome  information  to  many  steel  users. 

If  the  physical  properties  of  steels  of  various  types  are  affected 
by  the  nature  and  quantity  of  the  occluded  gases  which  they  contained, 
it  seems  fair  to  inquire  whether  it  might  not  be  true  that  these  same 
factors  might  exert  an  important  influence  on  the  much  dis- 
cussed question  of  corrosion  resistance  in  relation  to  the  chemical 
constitution  of  iron  and  steel. 

The  alleged  good  or  bad  effect  of  minute  differences  in  the  per- 
centage composition  of  the  metal  has  been  so  much  discussed  and 
argued  about  by  a  great  number  of  investigators,  that  there  is  little  left 
to  be  said  or  claimed  in  regard  to  the  influence  of  these  solid  constituents. 
The  effect  of  gas  content  has,  however,  been  curiously  overlooked 
in  the  discussion  of  corrosion  problems  heretofore,  and  yet  it  is  proba- 
ble that  this  one  factor  is  the  most  important  of  all  with  relation  to 
all  the  commercial  metals,  no  matter  whether  we  are  considering  a 
steel  roofing  sheet  or  a  brass  or  bronze  condenser  tube. 

Of  the  atmospheric  corrosion  tests  consisting  of  many  hundred 
full  sized  corrugated  sheets,  which  have  been  described,  exactly  thir- 
teen sheets  out  of  about  six  hundred  of  the  same  age  were  found  to 
have  failed  in  periods  ranging  from  13  months  to  three  years.  It  at 
once  occurred  to  us  that  it  would  be  interesting  to  select  samples  from 
ten  of  these  failed  sheets,  and,  after  cleaning  off  the  adherent  rust 
with  hydrochloric  acid,  have  nitrogen  and  carbon  monoxide  deter- 
minations made,  which  would  then  be  compared  with  similar  analyses 
made  from  ten  sheets  taken  at  random,  that  were  still  in  excellent 


28 


RESEARCH  ON  CORROSION 


PURE  IRON  NAILS  TAKEN  FROM  GRAVE 
OF  SOLDIER  AFTER  BEING  BURIED  FOR 
100  YEARS  IN  FORT  ST.  CLAIR 
CEMETERY,  EATON,   OHIO. 


ANALYSIS  OF  NAILS 


Sulphur 

Phosphorus 

Carbon 

Manganese 

Copper 

Silicon 

Oxygen 

Hydrogen 

Nitrogen 

Iron 


.007 
.100 
.020 
.004 
trace 
trace 
.031 
trace 
.008 
99.830 


RESEARCH  ON  CORROSION 


29 


condition  on  the  test  rack.  Fortunately,  in  some  instances  strips  of 
the  original  test  sheets  as  they  were  before  exposure  had  been  pre- 
served so  that  it  was  possible  also  to  determine  if  any  change  of  chem- 
ical composition  of  the  base  metal  had  occurred  during  the  three 
years  of  outdoor  exposure.  This  work  was  immediately  put  under 
way,  with  the  following  results: 


GOOD  SHEETS 

BAD  SHEETS 

Sheet  No. 

Carbon 
Monoxide 

Nitrogen 

Sheet  No. 

Carbon 
Monoxide 

Nitrogen 

250 

.003 

.007 

88 

.011 

.014 

241 

.005 

.006 

91 

.016 

.015 

266 

.006 

.004 

529 

.012 

.032 

252 

.003 

.003 

626 

.016 

.016 

337 

.009 

.005 

625 

.024 

.021 

290 

.016 

.005 

530 

.014 

.017 

336 

.011 

.003 

623 

.013 

.011 

662 

.019 

.004 

624 

.021 

.006 

299 

.014 

.003 

531 

.015 

.019 

435 

.012 

.003 

101 

.027 

.006 

The  bad  sheets  which  failed,  referred  to  in  the  above  table,  had 
all  been  purchased  in  the  open  market  as  examples  of  typical  Bessemer 
steels,  but  the  present  point  of  interest  in  connection  with  them  is 
the  fact  that  they  showed  by  analysis  from  two  to  five  times  the  con- 
tent of  nitride  nitrogen  shown  by  the  companion  sheets  which  had 
not  failed. 

Taken  in  conjunction  with  the  great  difference  in  lasting  quality 
of  the  two  sets  of  sheets,  the  results  are  suggestive  and  significant. 
In  the  course  of  our  experience  a  number  of  cases  had  been  brought 
to  our  attention,  in  which  steel  in  various  kinds  of  service  had  failed 
in  an  extraordinary  manner  and  in  comparatively  brief  periods  of 
time.  Previous  chemical  analyses  that  had  been  made  for  the  usual 
solid  impurities,  as  well  as  microscopic  examinations  had  not  as  usual 
revealed  the  reason  for  the  sudden  corrosion  of  the  materials.  In 
view  of  the  significance  of  the  results  shown  in  the  above  table,  how- 
ever, it  became  a  matter  of  interest  to  see  what  a  complete  analysis, 
including  all  gases,  would  indicate.  The  first  case  was  that  of  a  steel 
pipe  which  was  perforated  with  holes  after  being  buried  for  14  months 
in  an  alkali  soil.  The  second  case  is  that  of  some  railroad  spikes  that 
had  corroded  in  an  unusual  and  dangerous  manner  after  being  in  use 
only  a  few  years.  An  illustration  of  these  failures  is  given. 
The  results  of  the  analysis  of  these  failures  is  given  in  the  following 
Table — and  for  the  purpose  of  comparison  the  analysis  of  a  very 
pure  open  hearth  iron  is  also  given : 


30 


RESEARCH  ON  CORROSION 


FAILURE   OF   STEEL   PIPE    AFTER    14 

MONTHS  IN  ALKALI  SOIL  DUE 

TO  HIGH  NITROGEN 

ANALYSIS 

Silicon trace 

Sulphur 049 

Phosphorus 098 

Carbon 090 

Manganese 357 

Copper 014 

Oxygen 032 

Hydrogen trace 

Nitrogen 041 

Iron  .  . .99.319 


RESEARCH  ON  CORROSION  31 

COMPARATIVE  ANALYSIS  OF  STEEL  AND 
ARMCO  INGOT  IRON 

Pipe  Spike  Armco 

Failure  Failure  Ingot  Iron 

Carbon 090  .100  .010 

Manganese 357  .405  .025 

Phosphorus 098  .108  .004 

Sulphur 049  .041  .025 

Silicon trace  trace  trace 

Copper 014  trace  .040 

Nitrogen .041  .033  .004 

Oxygen 032  .082  .015 

Carbon  Monoxide 052  .058  .015 

Carbon  Dioxide trace  trace  trace 

Hydrogen trace  trace  trace 

Other  instances  like  the  above,  in  which  rapid  failure  has  been 
accompanied  by  high  nitride  nitrogen  content  have  been  found,  but 
as  the  present  intention  is  rather  to  inquire  into  the  subject  than  to 
arrive  at  final  conclusions,  a  slightly  different  phase  of  the  subject 
will  now  be  referred  to. 

Among  the  examples  of  Bessemer  steels  included  in  the  atmos- 
pheric exposure  tests  above  referred  to,  Sheet  No.  531  of  Bessemer 
steel  was  perforated  with  numerous  rust  holes  in  13  months,  as  was 
also  sheet  No.  88.  Sheet  No.  624  also  of  Bessemer  steel  did  not  fail 
until  33  months  of  exposure.  The  complete  analyses  of  these  three 
samples  is  given  in  the  following  table: 

Good  Bessemer  Poor  Bessemer  Poor  Bessemer 

Sheet  No.  624  Sheet  No.  88  Sheet  531 

Carbon .010  .030  .015 

Manganese .480  .400  .310 

Phosphorus .082  .064  .060 

Sulphur .044  .031  .063 

Copper trace  .028  .010 

Carbon  Monoxide .021  .011  .015 

Oxygen .055  .031  .071 

Nitrogen. .006  .014  .019 

In  view  of  the  great  difference  in  lasting  quality  under  atmos- 
pheric corrosion,  these  analyses  are  a'gain  suggestive.  The  nitride 
nitrogen  of  the  two  poor  sheets  is,  however,  from  2  to  3  times  higher 
in  the  poor  sheets  than  in  the  good  sheet. 

It  has  frequently  been  noted  by  a  number  of  investigators  that 
sheets  that  fail  rapidly  under  atmospheric  corrosion  tests  cover  them- 
selves with  a  much  lighter  colored  and  more  loosely  adherent  rust 
than  the  more  resistant  sheets. 

We  heated  small  samples  of  iron  and  steel  in  an  atmosphere  of 
ammonia  gas,  and  thereby  raised  the  content  of  nitride  nitrogen. 


32 


RESEARCH  ON  CORROSION 


FAILURE  OF  STEEL  JRAILROAD   SPIKES 

AFTER  A  FEW  YEARS  DUE  TO 

HIGH    NITROGEN 


ANALYSIS 


Silicon  .... 
Sulphur.  .  .  . 
Phosphorus 
Carbon.  .  .  . 
Manganese 
Copper.  .  .  . 
Oxygen  .  .  . 
Hydrogen  . 
Nitrogen 
Iron  . 


.  trace 
.  .041 
.  .108 
.  .100 
.  .405 
.  trace 
.  .082 
trace 
033 
.99.231 


RESEARCH  OX  CORROSION  33 

In  every  case  it  has  been  found  that  with  increased  nitrogen  content 
the  attack  of  dilute  acid  on  the  specimen  is  stimulated.  Two  samples 
of  pure  iron  were  cut  from  the  same  sheet  containing  a  normal  con- 
tent of  nitride  nitrogen  of  .003  per  cent.  One  of  these  samples  was 
heated  in  ammonia  gas  until  the  nitrogen  had  risen  to  .127  per  cent. 
The  two  samples  w^ere  then  suspended  side  by  side  in  25  per  cent 
sulphuric  acid.  The  nitrified  sample  was  destroyed  in  6  days,  while 
the  untreated  sample  lasted  11  days.  Unfortunately,  no  rational 
corrosion  test  is  known,  so  that  it  has  been  impossible  up  to  this 
time  to  test  the  corrosion  resistance  under  atmospheric  or  various 
forms  of  service  exposure,  of  test  pieces  that  have  had  the  nitrogen 
content  increased  by  artificial  means. 

In  the  attempt  to  find  an  explanation  of  why  high  fixed  nitrogen 
and  high  gas  content  stimulate  rapid  corrosion,  we  feel  justified  in 
stating  that  there  is  a  considerable  body  of  evidence  which  points  in 
the  direction  of  combined  and  occluded  gas  as  being  a  very  important 
factor  in  the  corrosion  resistance  of  various  types  of  metal. 

We  have  in  our  collections  numerous  examples  of  the  old,  hand 
forged,  ancient  irons  that  have  shown  very  extraordinary  resistance 
to  corrosion  under  exposure,  lasting  in  some  cases  for  many  centuries. 
It  has  always  been  a  mystery,  what  gave  these  old  irons  their  dura- 
bility. With  the  repeated  reheatings  and  hammering  that  these 
hand  forged  metals  underwent,  it  is  reasonable  to  suppose  that  they 
were  wonderfully  densified  and  degasified.  They  have  always  shown 
themselves  to  contain  very  low  percentages  of  nitrogen. 


34 


RESEARCH  ON  CORROSION 


LJ  U 

U  C.) 

ID  O  O  O  <  < 

n  CM  co  -  ct  tr 

o  o  o  ^  h-  i 


<  J  O 
01  O 


[fl  -  !f)  CM  ID  O 

CM  CM  -  sr  --  n 

O  O  O  O  N  CD 


I 


3  U 

cr  on 

no  u 

3  I  Z  Z 

I  ff  O  < 

CL  (/)  m  o 

j  o  o:  z 

3  I  < '  < 

(/)  CL  (^  Z 


n  CD  o  Q  <  o 
n  o  r^  h  rr  CD 

a  o  -  n  h  ^r 


U 
M 

U 
Z 

I  il  O  < 

Q_  in  03  CD 

j  o  or  z 

3  I  <   < 


tn  o 

3  I 


Q_  U  I  GO'  U 


MAGNETIC  TESTING 


36 


MAGNETIC  TESTING  OF  ELECTRIC  SHEETS 


MAGNETIC  TESTING  OF  ELECTRIC  SHEETS. 

|LECTRICAL  sheet  steel  products  are  today  bought  and 
sold  on  specification  requiring  careful  tests  for  magnetic 
properties,  both  by  the  producer  and  consumer. 
If  the  consumer  does  not  have  the  facilities  for  magnetic 
testing  he  must  rely  upon  the  producer,  and  in  this  case 
it  is  well  for  him  to  know  in  detail  what  methods 
are  being  used. 

It  is  for  the  special  benefit  of  this  class  of  customers  that  we  in- 
clude the  following  paragraphs  in  this  book.  Others  who  are  more  ad- 
vanced in  magnetic  testing  wTill  find  the  information  useful  in  compar- 
ing results. 

CORE  LOSS  TEST 

The  power  consumption  in  electrical  sheet  steel,  when  subjected 
to  an  alternating  magnetization  is  known  as  the  core  loss.  The  stand- 
ard core  loss  is  the  total  power  in  w^atts  consumed  in  each  kilogram  of 
material  at  a  temperature  of  25  degrees  C  when  subjected  to  a  har- 
monically varying  induction,  having  a  maximum  of  10,000  gausses  and 
a  frequency  of  60  cycles  per  second.  It  is  represented  by  the  symbol 
W  10/60. 

The  method  of  test  which  we  use  is  an  outgrowth  of  that  orig- 
inally used  by  Professor  Epstein  and  adopted  by  The  American  Society 
for  Testing  Materials  in  1911.  A  photograph  shows  the  arrange- 
ment of  coils  and  sample  pieces. 

The  magnetic  circuit  consists  of  10  kg.  (22  Ibs.)  of  the  test  materi- 
al, cut  with  a  sharp  shear  into  strips  50  cm.  (19  11/16  ins.)  long  and 
3  cm.  (1  3-16  ins.)  wide,  half  parallel  and  half  at  right  angles  to  the 
direction  of  rolling,  made  up  into  four  equal  bundles,  two  containing 
material  parallel  and  two  containing  material  at  right  angles  to  the 
direction  of  rolling,  and  finally  built  into  the  four  sides  of  a  square 
with  butt  joints  and  opposite  sides  consisting  of  material  cut  in  the 
same  manner.  No  insulation  other  than  the  natural  scale  of  the  ma- 
terial (except  in  the  case  of  scale-free  material)  shall  be  used  between 
laminations,  but  the  corner  joints  shall  be  separated  by  tough  paper 
0.01  cm.  (0.004  in.)  thick. 

37 


38  MAGNETIC  TESTING  OF  ELECTRIC  SHEETS 


TESTING  COILS— Epstein  Core  loss  tests 


MAGNETIC  TESTING  OF  ELECTRIC  SHEETS  39 

The  magnetizing  winding  consists  of  four  solenoids  surrounding 
the  four  sides  of  the  magnetic  circuit  and  joined  in  series.  A  sec- 
ondary coil  is  used  for  energizing  the  voltmeter  and  the  potential  coil 
of  the  wattmeter. 

These  solenoids  are  wound  on  a  form  of  any  non-magnetic  non- 
conducting material  of  the  following  dimensions: 

Inside  cross-section  ....................  4  by  4  cm. 

Thickness  of  wall  ................  not  over  0.3  cm. 

Winding  length  ..........................  42  cm. 

The  primary  winding  on  each  solenoid  consists  of  150  turns  of 
copper  wire  uniformly  wound  over  the  42  cm.  length.  The  total  re- 
sistance of  the  magnetizing  winding  is  between  0.3  and  0.5  ohm.  The 
secondary  winding  of  150  turns  of  copper  wire  on  each  solenoid  is 
similarly  wound  beneath  the  primary  winding.  Its  resistance  should 
not  exceed  1  ohm. 

A  voltmeter  and  the  voltage  coil  of  a  wattmeter  are  connected 
in  a  parallel  to  the  terminals  of  the  secondary  winding  of  the  apparatus. 
The  current  coil  of  the  wattmeter  is  connected  in  series  with  the  pri- 
mary winding. 

A  sine  wave  electromotive  force  is  applied  to  the  primary  wind- 
ing and  adjusted  until  the  voltage  of  the  secondary  circuit  is  given 
by  the  equation: 

4fNnBM 


41D108 
in  which 

f     =form  factor  of  primary  E.  M.  F.       =1.11  for  sine  wave 
N  =  number  of  secondary  turns  =  600 

n  number  of  cycles  per  second  =  60 

B   =  maximum  induction  =10,000 

M  =  total  mass  in  grams  =  10,000 

1     =  length  of  strips  in  centimeters  =50 

D  =  specific  gravity  =  7.  5  for  high-resistance  steel 
7.7  for  low-resistance  steel 

E  =  106.6  volts  for  high-resistance  steel  for  sine  voltage. 
=  103.8  volts  for  low-resistance  steel  for  sine  voltage. 

A  specific  gravity  of  7.5  is  assumed  for  all  steels  having  a  resis- 
tance of  over  2  ohms  per  meter-gram,  and  7.7  for  all  steels  having  a 


40 


MAGNETIC  TESTING  OF  ELECTRIC  SHEETS 


O 
be 


MAGNETIC  TESTING  OF  ELECTRIC  SHEETS  41 

resistance  of  less  than  2  ohms  per  meter-gram.  These  steels  are  desig- 
nated as  high  and  low  resistance  steels,  respectively. 

The  wattmeter  gives  the  power  consumed  in  the  iron  and  the 
secondary  circuit.  The  loss  in  the  secondary  circuit  is  given  in  terms 
of  the  total  resistance  and  voltage.  Subtracting  this  correction  term 
from  the  total  power  gives  the  net  power  consumed  in  the  steel  as 
hysteresis  and  eddy  current  loss.  Dividing  this  value  by  ten  gives 
the  core  loss  in  w^atts  per  kilogram. 

Sampling  —  From  each  annealing  box  of  material  we  take 
sample  sheets  from  top,  center  and  bottom.  Each  sample  repre- 
senting not  over  10,000  Ibs.  of  material.  If  there  is  more  than  one 
heat  of  steel  in  the  box  the  samples  are  so  taken  to  represent  each  heat. 
All  samples  are  recorded  by  box  number,  position  of  lot  and  heat 
number. 

Procedure  —  1.  Cut  the  test  material  into  strips  3  x  50  cm., 
half  parallel  and  half  at  right  angles  to  the  direction  of  rolling. 

2.  Place  on  the  balance  a  pile  of  strips  weighing  2.5  kg.     Add 
a  second  pile  of  the  same  kind,  bringing  the  weight  up  to  5  kg.     In 
each  case  the  weight  is  taken  to  the  nearest  strip.     Add  in  succession 
two  piles  of  2.5  kg.  each,  of  the  other  kind  of  strips,  bringing  the  weight 
up  to  7.5  kg.  and  10  kg.  respectively. 

3.  Secure  each  bundle  by  string  or  tape  (not  wire)  and  insert 
in  the  apparatus  as  indicated. 

4.  Apply  the  alternating  voltage  to  the  primary  coil  and  tap 
the  joints  together  until  the  current  has  a  minimum  value,  as  shown 
by  an  ammeter  in  series.     Then  clamp  the  corners  firmly  by  some 
suitable  device. 

5.  Shunt  the  ammeter  and  adjust  the  primary  current  until  the 
voltmeter  indicates  the  proper  value.     This  adjustment  may  be  made 
by  an  auto-transformer,  by  varying  the  field  of  the  alternator,  or  by 
both,  but  not  by  the  insertion  of  resistance  or  inductance  in  the  pri- 
mary circuit.     Simultaneously   the   frequency  must  be  adjusted   to 
60  cycles. 

6.  Read  the  wattmeter. 

7.  Calculations.     Subtract  from  the  wattmeter  reading  the  in- 
strument losses,  which  will  be  constant  for  any  set  of  instruments  and 
voltage,  and  divide  by  10.     The  result  is  the  standard  core  loss. 


42 


MAGNETIC  TESTING  OF  ELECTRIC  SHEETS 


.      MAGNETIC  TESTING  OF  ELECTRIC  SHEETS  43 

AGING  TESTS 

Sheet  steel  after  annealing  is  peculiar  in  its  magnetic  behavior 
and  tends  to  go  back  to  the  unannealed  state  when  continuously  sub- 
jected to  temperatures  somewhat  above  normal  room  temperature. 
This  increase  in  core  loss  is  known  as  aging  and  is  generally  expressed 
as  an  aging  coefficient  in  percent  based  on  the  initial  core  loss. 

The  standard  test  is  based  on  a  heating  at  100  degrees  C  for  600 
hours  in  a  constant  temperature  oven  such  as  shown  in  the  accompany- 
ing photograph.  Core  loss  tests  to  be  made  before  and  after  the 
heating  period. 

PERMEABILITY  TESTS 

The  above  title  is  used  in  general  to  cover  tests  necessary  to  ob- 
tain data  for  normal  induction  curves  or  magnetization  and  satura- 
tion curves  as  they  are  sometimes  called.  From  this  data  permea- 
bility values  may  be  calculated  and  actual  permeability  curves  plotted. 

For  this  test  we  use  the  Burrows  compensated  double  yoke 
method  (described  in  the  standard  Hand-book  for  Electrical  Engineers 
and  also  in  Technical  Paper  No.  117  of  the  Bureau  of  Standards.) 
A  photograph  shows  the  apparatus  as  used  in  our  laboratory. 

The  normal  magnetic  induction  is  the  induction  produced  by  a 
magnetizing  force  in  a  given  piece  of  magnetic  material  which  has 
been  previously  demagnetized  and  then  subjected  to  many  reversals 
of  the  given  magnetizing  force. 

Both  the  induction  B  and  the  magnetization  force  H  is  expressed 
in  terms  of  the  C.  G.  S.  electromagnetic  unit  (gauss). 

The  test  material  consist  of  5  kg.  of  the  strips  cut  as  indicated 
for  the  standard  core  loss  test. 

The  magnetic  circuit  is  a  rectangle  having  the  test  material  for 
one  pair  of  opposite  sides,  and  the  same  or  different  material  for  the 
other  pair,  which  may  be  shorter.  The  joints  at  each  corner  are 
alternately  butt  and  lap,  or  may  be  clamped  on  the  edges. 

The  magnetomotive  force  is  applied  in  two  sections.  The  main 
magnetizing  coils  consists  of  two  equal  and  uniformly  wound  sole- 
noids surrounding  the  test  material.  The  compensating  coils  con- 
sist of  two  solenoids  surrounding  the  yoke  strips. 

The  test  coil  surrounds  the  middle  portion  of  each  bundle  of 
test  material.  Four  other  test  coils  of  half  the  number  of  turns  are 


44 


MAGNETIC  TESTING  OF  ELECTRIC  SHEETS 


a 

g 
'I 

o 

I 


MAGNETIC  TESTING  OF  ELECTRIC  SHEETS  45 

placed  over  the  test  material,  approximately  midway  between  the 
yokes  and  the  center.  The  two  center  test  coils  are  joined  in  series 
and  the  four  end  test  coils  are  joined  in  series.  The  corresponding 
ballistic  deflections,  due  to  these  two  test  coils,  are  measures  of  the 
magnetic  fluxes  through  the  underlying  portions  of  the  magnetic  cir- 
cuit. By  connecting  the  two  test  coils  so  that  the  induced  electro- 
motive forces  oppose  each  other,  and  adjusting  the  current  through 
the  compensating  magnetizing  coils  so  that  there  is  no  resulting  ballis- 
tic deflection,  an  approximate  uniformity  of  flux  is  secured  through 
the  greater  portion  of  the  test  material,  and  the  induction  may  be 
measured  ballistically  in  the  regular  manner.  The  magnetizing  force 
when  the  flux  is  adjusted  to  uniformity  is  that  calculated  from  the 
uniform  winding  of  the  main  magnetizing  solenoids. 

The  cross-section  of  the  magnetic  circuit  is  determined  as  in  the 
standard  core  loss  test. 

For  curve  work  we  obtain  magnetizing  force  or  H  values  corres- 
ponding to  induction  values  "B"  of  from  2000  to  20,000  gausses  by 
steps  of  2000. 

For  obtaining  permeability  values  at  low  and  high  inductions  we 
determine  "H"  values  for  three  values  of  "B"  namely  6000,  10,000 
and  16,000  gausses. 

For  routine  commercial  testing  we  find  the  above  values  very 
satisfactory  for  checking  and  comparisons. 


METALLURGICAL  CONTROL 

MICROSCOPICAL  AND 
PHYSICAL     TESTING 


48 


METALLURGICAL  CONTROL 


METALLURGICAL  CONTROL 


|N  addition  to  careful  and  constant  chemical  control  the  most 
exacting  metallurgical  supervision  is  necessary  in  the 
manufacture  of  "Armco"  products.  This  supervision 
begins  with  the  raw  materials  and  follows  through  every 
operation  to  the  finished  product.  A  constant  watch  is 
kept  upon  the  quality  of  the  raw  materials  to  insure  that 
they  are  suitable  to  enter  into  the  manufacture  of  Armco  quality 
materials.  In  the  Open  Hearth  Department  in  addition  to  the  vigilant 
chemical  control,  a  record  is  kept  of  the  pouring  temperatures  of  all 
heats  and  the  greatest  care  is  used  to  maintain  uniform  pouring  tem- 
peratures. These  temperatures  are  measured  by  means  of  optical 
pyrometers  which  will  be  described  later.  In  the  Blooming,  Bar  and 
Sheet  Mills  every  care  and  precaution  is  used  to  see  that  the  materials 
are  fabricated  in  a  manner  to  produce  the  highest  quality  products. 
The  conditions  of  manufacture  are  watched  continuously  by  the 
Operating  and  Research  Departments  to  see  that  they  remain  con- 
stant and  do  not  vary  from  Armco  standards.  In  the  Annealing  De- 
partment where  improper  heat  treatment  can  so  readily  produce  un- 
desirable properties  in  the  sheets,  a  complete  system  of  thermoelectric 
pyrometers  is  installed  to  record  and  to  facilitate  the  control  of  an- 
nealing temperatures.  In  the  Galvanizing  Department  thermoelectric 
pyrometers  are  also  installed  to  safeguard  the  uniformity  of  manu- 
facturing operations  and  thereby  to  insure  the  maintenance  of  Armco 
quality.  In  the  Finishing  Department  the  quality  of  the  product  is 
carefully  tested  and  proved  by  microscopic  and  ductility  tests  as  well 
as  by  thorough  visual  inspection.  In  fact  throughout  the  whole 
mill  every  manufacturing  operation  is  surrounded  with  every 
safeguard  which  experience  and  science  can  devise  to  insure  the 
greatest  uniformity  and  the  highest  quality  in  the  finished 
products. 

49 


50 


METALLURGICAL  CONTROL 


METALLURGICAL  CONTROL  51 

SCIENTIFIC  HEAT  TREATMENT 

It  is  probable  that  the  greatest  advance  which  has  been  made 
in  the  metallurgy  of  iron  and  steel  in  recent  years  is  the  development 
of  heat  treatment  upon  a  scientific  basis.  It  has  not  been  a  great 
improvement  in  the  art  made  at  a  single  step  by  a  single  invention 
or  discovery,  as  some  of  the  improvements  in  the  past,  such  as  the 
Bessemer  converter  and  the  Siemens  regenerative  furnace.  But 
scientific  heat  treatment  has  been  a  gradual  development,  the  result 
of  much  painstaking  investigation  and  research  upon  the  part  of 
many  metallurgists.  The  fuller  understanding  of  its  principles  and 
the  broader  application  of  them  has  resulted  in  higher  quality  in 
iron  and  steel  products  than  was  formerly  thought  possible. 

Heat  treatment  to  the  metallurgist  means  the  application  of 
heat  or  rather  the  manipulation  of  heat  for  the  purpose  of  producing 
desired  physical  or  structural  properties  in  the  material  treated. 
Furthermore  heat  treatment  is  usually  applied  to  finished  or  semi- 
finished material.  In  the  forging  or  rolling  of  metal,  stresses  and 
strains  are  set  up  and  only  by  heat  treatment  can  they  be  removed. 
This  heat  treatment  when  done  at  the  proper  time  and  temperature, 
produces  physical  changes  in  the  metal  giving  it  the  desired  proper- 
ties. 

In  the  sheet  metal  industry  this  heat  treatment  is  called  annealing. 
It  has  been  found  that  the  length  of  time  and  the  uniformity  of  the 
temperature  are  important  factors.  Improper  annealing  can  ruin  a 
sheet  of  metal  for  the  purpose  intended.  It  can  make  a  soft  sheet 
extremely  brittle,  yet  re-annealing  this  material  under  proper  con- 
ditions will  bring  it  back  again  as  ductile  as  before. 

Especially  in  meeting  the  demands  for  a  high  finished  or  glossy 
sheet  with  deep  drawing  properties  as  demanded  for  automobile 
bodies  and  fenders,  heat  treatment  has  made  a  most  important 
contribution  to  the  industries  of  today. 

The  presence  of  strains  in  the  sheets  due  to  the  rolling  is  also  a 
contributing  factor  towards  rapid  corrosion  and  it  has  been  found 
necessary  to  relieve  such  strains  before  coating  as  in  the  case  of 
galvanized  sheets  which  are  to  be  used  under  exposure  to  the  elements. 

The  narrow  range  between  good  and  bad  heat  treatment  can 
best  be  controlled  by  the  use  of  metallurgical  microscopes  which 
reveal  the  grain  structure  for  examination.  Microscropic  exam- 
ination serves  as  a  guide  in  obtaining  a  standard  and  uniform  heat 


52 


METALLURGICAL  CONTROL 


METALLURGICAL  CONTROL  53 

treatment  in  the  manufacture  of  the  product.  An  example  of  the 
results  of  proper  and  improper  annealing  as  detected  by  the  micro- 
scope is  shown  on  page  54.  Both  micrographs  were  taken  from 
the  same  piece  of  steel;  one  after  having  been  improperly  annealed, 
and  the  other  after  having  been  properly  annealed.  The  elongated 
grains  and  the  strained  condition  of  the  metal  is  readily  seen  in  the 
improperly  annealed  sample,  and  may  be  compared  with  the  well- 
rounded  equiaxed  grains  in  the  properly  annealed  sample. 

Due  to  careful  scientific  research  the  organization  of  The 
American  Rolling  Mill  Company  has  been  able  to  produce  many 
specialties  in  the  iron  and  steel  line.  Notable  among  these  are 
American  Ingot  Iron,  Enameling  Sheets,  Automobile  Sheets,  Deep 
Drawing  Sheets  and  sheets  for  electrical  machinery,  such  as,  trans- 
formers, motors  and  generators.  In  addition,  billets  are  supplied 
from  which  wire  is  made  with  high  electrical  conductivity  for  use 
in  telegraph  and  telephone  lines.  Billets  are  also  furnished  for  the 
manufacture  of  welding  rods  and  wire  for  the  Electric  or  Acetylene 
Gas  Welding  of  iron  and  steel  plates  or  castings. 


METALLURGICAL  CONTROL 


<D 

a 

I 


c 

aj 

8, 

2 

a 


IS     8 


bo 

bJO 
C 

I 


03  00 
bfi  CO 
C 


METALLURGICAL  CONTROL  55 


THERMOELECTRIC  AND  OPTICAL  PYROMETERS 

The  thermoelectric  pyrometer  equipment  which  The  American 
Rolling  Mill  Company  has  adopted  as  standard  for  plant  installations 
consists  of  base  metal  couples,  and  indicating  and  recording  poten- 
tiometers for  taking  millivoltage  readings.  When  necessary  an  alloy 
lead  wire  is  used  to  carry  the  cold  end  to  the  potentiometer,  where 
automatic  correction  for  the  cold  end  temperature  is  made. 

This  base  metal  thermoelectric  equipment  is  suitable  for  con- 
tinuous service  at  all  temperatures  up  to  about  1600  degrees  Fahren- 
heit. For  temperatures  above  this,  rare  metal  couples  are  used  or 
another  type  of  equipment,  such  as  optical  pyrometers. 

All  service  instruments  are  checked  at  thirty  day  periods  against 
a  standard  indicating  potentiometer  in  the  Research  Department. 

Thermocouples  are  checked  and  calibrated  in  the  laboratory  by 
comparison  with  standard  platinum,  platinum-rhodium  couples  which 
have  been  checked  against  a  master  couple  calibrated  by  the  Bureau 
of  Standards  at  Washington. 

Base  metal  couples  which  have  been  carefully  checked  in  the  labo- 
ratory are  sometimes  used  as  portable  standards  for  checking  in  the 
mill.  . 

Pouring  temperatures  in  the  Open  Hearth  Department,  Soaking 
Pit  temperatures  and  temperatures  of  hot  ingots  must  be  taken  with 
a  radiation  or  optical  type  of  pyrometer.  For  this  work  we  use 
an  optical  pyrometer.  This  instrument  will  measure  temperatures 
from  1200  to  4000  degrees  Fahrenheit. 


56 


METALLURGICAL  CONTROL 


METALLURGICAL  CONTROL  57 


MICROSCOPIC  TESTS 

The  Research  Department  is  equipped  with  the  latest  and  best 
equipment  and  accessories  for  the  microscopic  examination  of  metals. 
A  photograph  shows  the  inverted  micro-metallograph  used  for  this 
purpose.  This  is  the  equipment  as  perfected  by  Professor  Sauveur 
of  Harvard  University,  and  manufactured  by  the  Bausch  and  Lomb 
Optical  Company.  This  inverted  type  of  instrument  is  invaluable 
for  Research  work,  enabling  relatively  large  specimens  to  be  sup- 
ported on  the  stage  and  examined  with  ease. 

The  microscope  has  proved  itself  invaluable  to  the  iron  and 
steel  metallurgist  because  of  the  information  it  discloses  as  to  the 
physical  structure  of  metals.  Its  extended  use  has  been  linked 
closely  with  the  development  of  heat  treatment  for  only  by  means 
of  the  microscope  can  the  structural  changes  produced  by  heat 
treatment  and  annealing  be  observed. 

Because  of  the  close  relation  between  annealing  temperatures 
and  grain  size  we  have  found  the  microscope  to  be  a  reliable  index 
of  the  quality  of  the  annealing,  and  a  check  by  means  of  the  micro- 
scope is  made  on  every  lot  of  sheets  annealed.  For  this  purpose 
one  sheet  is  selected  from  near  the  top  and  the  bottom  of  every 
annealing  lot.  A  strip  twelve  (12)  inches  wride  is  cut  from  the  end 
of  each  sheet  and  from  the  center  of  the  freshly  sheared  edge  of  the 
strip  we  cut  a  small  sample  about  */%'  x  1J4"  for  microscopic  exam- 
ination. 

The  sample  is  selected  in  this  manner  in  order  to  have  it  represen- 
tative, it  having  been  proved  by  experience  that  a  sample  taken  from 
this  location  is  fairly  representative  of  the  whole  sheet.  The  sample 
thus  secured  is  polished,  etched,  and  carefully  examined  and  a  record 
made  of  the  quality  of  the  annealing  as  indicated  by  the  micro- 
structure.  No  annealing  lot  which  shows  any  indication  of  improper 
treatment  is  allowed  to  pass. 


58 


METALLURGICAL  CONTROL 


Four  disc  polishing  table  showing  arrangements  for  polishing  specimens  for 
microscopical  examination 


METALLURGICAL  CONTROL  59 

Polishing  Methods. 

The  specimen  for  microscopical  examination  is  first  ground  on 
an  emery  wheel  until  the  surface  oxide,  mat,  etc.,  are  removed  and 
the  specimen  is  flat.  A  four  disc  machine  made  by  the  University 
of  Michigan  is  used  to  complete  the  polishing.  The  specimen  is 
next  ground  on  No.  000  emery  cloth  mounted  on  the  first  disc  of 
the  machine.  Then  the  specimen  is  polished  on  the  second,  third, 
and  fourth  wheels  to  which  is  applied  3  F  alundum,  65  C  alundum 
and  levigated  alumina  respectively,  the  specimen  always  being  held 
so  that  the  scratches  run  at  right  angles  to  those  made  by  the  pre- 
ceding abrasive.  Polishing  is  continued  with  each  abrasive  until 
the  scratches  made  by  the  preceding  one  are  removed. 

The  abrasives  with  the  proper  amount  of  water  are  placed  in 
ordinary  5-pint  reagent  bottles,  fitted  writh  3-holed  rubber  stoppers. 
Compressed  air  for  agitation  is  introduced  through  one  hole,  the 
syphon  which  conducts  the  water  with  abrasive  in  suspension  to  the 
polishing  wheel  passes  through  another,  while  the  air  is  emitted 
from  the  bottle  through  the  third  one.  The  glass  tube  of  the  syphon 
is  broken  and  about  a  2"  section  of  rubber  tubing  inserted  so  that 
the  amount  of  abrasive  applied  to  the  polishing  disc  may  be  regulated 
by  means  of  a  pinchcock. 


Etching  Methods. 

Before  a  specimen  is  etched  writh  any  etching  solution  it  is  washed 
in  ethel  alcohol  to  remove  any  traces  of  oil  or  grease  from  the  sur- 
face that  might  cause  the  etching  to  take  place  unevenly.  After 
etching  with  the  ordinary  solutions  the  specimen  is  again  washed 
in  ethel  alcohol  to  stop  the  action  of  the  reagent  and  prevent  staining 
or  tarnishing.  After  washing,  the  specimen  is  dried  with  soft 
chamois  wThich  is  kept  free  from  minute  particles  of  dust  and  grit. 

For  rapid  etching  when  it  is  desired  to  examine  only  the  shape 
and  size  of  the  grains  an  etching  solution  composed  of  10  per  cent 
nitric  acid  and  90  per  cent  ethel  alcohol  is  used.  A  solution  of 
3  per  cent  nitric  acid  and  97  per  cent  ethel  alcohol  is  generally  used, 
and  for  ordinary  purposes  is  very  satisfactory  and  rapid. 

When  the  specimen  is  to  be  examined  minutely  it  is  etched  in 
a  solution  of  5  per  cent  picric  acid  and  95  per  cent  ethel  alcohol. 


60 


METALLURGICAL  CONTROL 


General  view  in  Physical  Testing  Section  of  Research  Department 


METALLURGICAL  CONTROL  61 

Picric  acid  as  received  contains  20  per  cent  water.  Better  results 
will  be  obtained  if  this  water  is  removed.  This  may  be  accomplished 
by  making  a  saturated  solution  of  the  picric  acid  in  hot  alcohol, 
allowing  it  to  cool  and  recrystallize,  and  then  filtering  and  drying. 
This  is  a  more  satisfactory  method  than  attempting  to  drive  off  the 
water  by  heating,  as  the  crystals  fuse  at  122°  and  explode  at  a  slightly 
higher  temperature. 

For  the  identification  of  pearlite  and  segregated  cementite  in  low 
carbon  steel  sheets  the  specimen  is  boiled  5  to  10  minutes  in  a  sodium 
picrate  solution.  To  prepare  this  solution  proceed  as  follows: 

Dissolve  25  grams  of  sodium  hydroxide  in  60  to  70  cc.  of  water, 
add  2  grams  of  picric  acid,  heat  the  solution  until  the  picric  acid  is 
dissolved,  and  then  bring  the  volume  up  to  100  cc.  by  adding  more 
water.  Before  etching  the  solution  should  be  brought  to  boiling. 
This  reagent  imparts  a  brown  or  blackish  color  to  cementite. 

Special  Methods. 

In  many  cases  heat-tinting  affords  valuable  information  when 
ordinary  etching  methods  fail.  Heat- tinting  was  originated  by  J.  E. 
Stead  and  is  described  by  him  as  follows: 

"Heat-tinting  consists  in  heating  polished  specimens  of  metals 
until  their  surfaces  become  colored  by  oxidation  films. 

"Alloys  of  iron  and  phosphorus,  and  commercial  steel,  contain 
part  of  their  mass  richer  in  phosphorus  than  other  portions.  In 
fact  the  iron  and  the  phosphide  are  seldom  intimately  mixed  in 
ordinary  steel.  When  polished  specimens  are  placed  on  the 
surface  of  a  molten  bath  of  tinman's  solder1,  and  the  heat  gradually 
raised,  the  portions  of  the  specimens  richest  in  phosphorus  assume 
oxidation  tints  earlier  than  the  purer  parts;  hence  it  follows  that 
by  the  time  the  phosphorus-rich  parts  have  passed  through  the 
transition  stages  of  yellow-brown,  to  red  and  purple,  the  purer 
portions  will  have  reached  the  yellow-brown  or  red  stage,  and  if 
at  this  point  the  specimen  be  removed  from  the  source  of  heat, 
the  phosphorus-rich  portions  w^ill  appear  under  the  microscope  as 
purple  or  blue  on  a  yellow-brown  or  red  background.  If  the 
heating  of  the  specimen  be  continued,  the  phosphorised  part  will 
assume  a  yellowish-white  tint,  while  the  purer  part  will  reach  the 
blue  stage.  Each  part  will  pass  through  the  complete  range  of 
color  from  yellow^  to  blue  and  then  to  nearly  white,  but  not  at 

1.  An  iron  plate  heated  by  a  bunsen  gas  burner  as  suggested  by  Sauveur  is  used. 


62 


METALLURGICAL  CONTROL 


Brinell  Hardness  Testing  Machine 


METALLURGICAL  CONTROL  63 

the  same  time,  because  the  purer  portions  always  lag  behind,  the 
degree  of  lag  depending  on  the  variation  in  the  proportions  of 
phosphorus  in  the  different  parts. 

"Heat- tinting  is  also  useful  in  intensifying  the  difference  in 
color  between  ferrous  sulphide  and  manganese  sulphide  when 
present  together  in  steel.  On  heating  polished  metal  containing 
inclusions  of  each  sulphide  until  it  appears  to  assume  a  uniform 
brown  tint,  the  ferrous  sulphide,  which  is  naturally  pale  yellow, 
will  be  found  under  the  microscope  to  have  been  colored  purple, 
while  the  manganese  sulphide,  naturally  a  pale  dove  color,  will 
have  become  white.  If  the  heating  be  continued  until  the  sur- 
rounding metal  becomes  blue,  the  ferrous  sulphide  will  be  blue 
and  the  manganese  sulphide  yellow. 

"To  obtain  good  results  by  heat-tinting,  it  is  absolutely  neces- 
sary first  to  apply  to  the  surface  a  very  dilute  solution  of  some 
acid  in  alcohol.  Picric  acid  answers  admirably,  but  care  must 
be  taken  to  remove  the  solution  employed  before  it  has  time  to 
develop  the  pearlite  or  sensibly  to  etch  the  metal.  After  thoroughly 
washing  the  specimen  in  water,  it  is  dried  with  a  perfectly  clean 
cloth  and  heated  on  a  hot  plate  to  about  150  deg.  C.  It  is  again 
rubbed  with  a  warm  clean  cloth,  and  is  then  ready  for  heating  to 
produce  the  color  tint. 

"It  is  difficult  to  explain  why  the  preliminary  acid  treatment 
is  necessary,  but  that  it  is  so  is  proved  in  practice,  for  if  it  is  omitted, 
the  tinting  is  always  unsatisfactory.  It  is  possible  that,  during 
polishing,  some  of  the  softer  metal  becomes  spread  over  the  harder 
part,  forming  an  exceedingly  thin  layer.  This,  however,  is  only  a 
surmise." 

In  the  course  of  many  research  investigations,  recourse  must 
be  had  to  special  methods  of  taking  and  preparing  samples.  Some- 
times samples  are  so  small  it  is  impossible  to  hold  them  for  polishing, 
in  which  case  they  are  soldered  to  a  large  piece  or  mounted  in  solder 
in  an  ordinary  pipe  cap.  Sometimes  it  is  desired  to  polish  and 
examine  sheets  on  edge.  In  that  case  the  samples  are  either  soldered 
together  or  bolted  with  small  stove  volts.  If  bolted  they  are  dipped 
in  melted  paraffin  before  polishing  so  that  the  paraffin  will  fill  up  the 
interstices  between  the  sheets,  which  would  otherwise  give  trouble 
when  the  specimen  was  etched. 


64 


METALLURGICAL  CONTROL 


W 


F'&c.  -^ga' 


3 
s 


sB§f 

iBx^^S;5 

c 

c 

2 
Q 

"8 

OJ 

ffi 

(-H 

AMETERS 

Kg 

w 


§ 

P^  W 

—  ft 

g 

O 


v^^^E 


g 


,,,„ 


METALLURGICAL  CONTROL 


65 


Ofttimes  it  is  desirable  to  use  special  etching  reagents.  For  the 
use  of  these  the  reader  is  referred  to  the  standard  books  on  Metallog- 
raphy by  A.  Sauveur  and  H.  M.  Howe,  and  to  the  American  Society 
for  Testing  Materials  Standards  for  1918,  page  771. 


66 


METALLURGICAL  CONTROL 


Erichsen  Draw  Testing  Machine  for  sheet  metal 


METALLURGICAL  CONTROL  67 


PHYSICAL  TESTS 

The  Physical  Testing  Section  of  the  Research  Department  is  well 
equipped  for  carrying  out  all  varieties  of  physical  tests  on  iron  and 
steel  products  as  well  as  other  materials  when  necessary.  This 
equipment  consists  of  a  number  of  the  more  usual  testing  machines 
and  several  of  more  unusual  ones.  The  following  is  a  partial  list  of 
the  equipment: 

One  100,OOCf  Ib.  Riehle  Universal  Testing  Machine. 
One  30,000  Ib.  Riehle  Universal  Testing  Machine. 
One*Hydraulic  Brinnell  Hardness  Testing  Machine. 
Several  Erichsen  Draw  Testing  Machines. 
One  Landgraf-Turner  Alternating  Stress  Testing  Machine. 

Several  Bend  Testing  Machines,  Scleroscope  Hardness  Testers, 
as  well  as  several  special  testing  machines  designed  for 
special  purposes. 

A  general  view  of  the  Physical  Testing  Section  is  shown  on  page 
60. 


Tensile  and  Brinell  Hardness  Tests. 

In  making  the  usual  Tensile  and  Brinell  Hardness  Tests,  the 
standardized  methods  adopted  by  the  American  Society  for  Testing 
Materials  are  used.  These  methods  are  described  in  the  1918 
Standards  of  the  American  Society  for  Testing  Materials,  page  759. 

In  addition  to  the  usual  tests  many  special  tensile  tests  are 
carried  out,  among  which  may  be  cited  tensile  tests  at  high  tempera- 
ture. In  these  tests  the  specimen  is  tested  while  enclosed  in  an 
electrically  heated  tubular  furnace  which  may  be  maintained  at  any 
desired  temperature. 


68 


METALLURGICAL  CONTROL 


Landgraf — Turner  Alternating  Stress  Testing  Machine 


METALLURGICAL  CONTROL  69 

Ductility  or  Draw  Test. 

The  ductility  or  draw  test  for  sheet  metal  is  made  on  the  Erichsen 
Draw  Testing  Machine,  a  photograph  of  which  is  shown  on  page  66. 
This  testing  machine  is  used  largely  in  research  investigations  in 
studying  the  drawing  qualities  of  steel  sheets  and  determining  how 
that  quality  is  affected  by  gauge,  annealing  temperature,  grain  size, 
and  other  factors. 

When  this  machine  is  being  used  on  a  research  investigation, 
samples  for  examination  are  taken  from  full  size  sheets  in  the  same 
manner  as  described  for  the  samples  for  micro-examination. 

Alternating  Stress  and  Impact  Tests. 

The  value  of  dynamic  tests  as  a  means  of  determining  the  real 
value  of  materials  for  various  engineering  purposes  where  live  loads 
are  encounteerd  is  becoming  more  and  more  evident.  While  testing 
methods  for  determining  dynamic  strength  have  not  as  yet  become 
stabilized  and  standard,  the  Physical  Testing  Section  is,  however, 
equipped  with  a  Landgraf-Turner  Alternating  Stress  Testing  Machine, 
as  well  as  impact  machines  of  special  design.  With  these  machines 
the  dynamic  strength  of  materials  under  investigation  is  studied. 


70 


METALLURGICAL  CONTROL 


x 
W 


METALLURGICAL  CONTROL  71 

THE  EXPERIMENTAL  FURNACE  ROOM 

Preparation  of  Alloys. 

The  Experimental  Furnace  Room  is  the  section  of  the  Research 
Department  where  the  preparation  of  experimental  alloys  is  carried 
out  on  a  small  scale,  as  well  as  annealing  and  heat  treating  experi- 
ments. The  room  is  fully  equipped  with  such  furnaces  as  are  neces- 
sary for  this  work,  as  well  as  pyrometers  for  accurate  control  of 
temperatures. 

The  furnace  equipment  which  is  all  electrically  heated  consists  of 
a  Hoskins  Crucible  Melting  Furnace  of  the  carbon  resistor  plate 
type,  a  Hdskins  Muffle  Annealing  Furnace,  and  a  small  arc  melting 
furnace.  The  crucible  melting  furnace  has  an  inside  chamber 
dimension  of  10"  x  10"  x  11".  It  will  conveniently  accommodate 
a  No.  18  graphite  crucible  and  will  melt  without  difficulty  forty  to 
fifty  pounds  of  pure  iron.  The  method  of  casting  experimental  melts 
is  shown  on  page  48.  It  consists  of  pouring  the  molten  metal  from 
the  crucible  into  a  3J/2-inch  square  split  ingot  mold.  A  forty-pound 
melt  gives  an  ingot  3J/^  inches  square  by  12  to  14  inches  long.  With 
this  furnace  any  alloy  or  series  of  alloys  may  be  prepared  in  large 
enough  quantities  so  that  the  physical,  chemical,  and  magnetic 
properties  may  be  determined.  It  is  possible  also  to  forge  the  small 
ingots  into  various  shapes  to  determine  the  forgeability  of  the  metal. 
The  small  ingots  may  even  be  rolled  into  sheets  to  determine  the 
properties  of  the  metal  in  sheet  form. 

Experimental  Heat  Treatment. 

Experimental  annealing  and  heat  treating  tests  are  carried  out  in 
the  Hoskins  Muffle  Furnace.  This  furnace  has  a  chamber  dimension 
of  8"  high  by  12"  wide  by  26"  long.  Temperatures  up  to  1800°  F., 
can  be  readily  obtained  and  steadily  maintained.  Small  annealing 
covers  and  other  auxiliary  equipment  for  duplicating  mill  annealing 
conditions  are  available. 

In  all  experimental  furnace  work  accurate  knowledge  of  tempera- 
tures is  essential.  The  room  is  amply  equipped  with  optical  and 
thermo-electric  pyrometers.  Indicating  and  recording  instruments 
are  available  and  all  are  carefully  checked  against  the  laboratory 
standards  whenever  thev  are  used. 


CHEMICAL  ANALYSIS 


74 


ALUMINUM 


I 


ALUMINUM  75 


ALUMINUM. 

KICHLINE1  METHOD   FOR  THE   DETERMINATION   OF 
ALUMINUM  OXIDE  AND  TOTAL  ALUMINUM 
IN  IRON  AND  STEEL. 

T  has  long  been  known  that  aluminum  oxide  when  freshly 
precipitated  is  readily  soluble  in  acids  and  when  strongly 
ignited  is  very  difficultly  soluble  in  acids. 

When  metallic  aluminum  is  added  to  steel  while  casting, 
its  tendency  is  to  unite  at  once  with  the  oxygen  existing 
in  the  steel,  both  as  metallic  oxides  and  as  CO  gas.  The 
products  of  this  reaction  are  Al^Os,  the  metals  of  the  oxides  reduced, 
and  carbon.  Since  in  regular  practice  there  is  only  sufficient  alu- 
minum added  to  "quiet  the  steel,"  the  aluminum  added  is  nearly  all 
converted  to  the  oxide  Al20s.  This  aluminum  oxide  is,  during  the 
operation,  heated  to  the  temperature  of  pouring  steel,  about  1600  to 
1650°  C.  (2912  to  3000  degrees  F.),  whereby  it  is  rendered  almost  en- 
tirely insoluble  in  dilute  hydrochloric  acid. 

In  order  to  test  the  effect  of  high  temperature  on  the  solubility 
of  Al20a  the  following  experiment  was  carried  out:  Ten  grams 
metallic  aluminum  were  dissolved  in  hydrochloric  acid,  boiled  low  and 
replaced  three  times  with  nitric  acid.  This  solution  of  aluminum 
nitrate  was  evaporated  to  dryness  to  drive  off  acid  fumes;  the  residue 
was  transferred  to  a  platinum  dish  and  placed  into  a  muffle  furnace 
where  the  temperature  was  gradually  raised  to  a  high  heat,  taking 
out  a  portion  at  intervals,  and  noting  the  temperature  each  time  with 
a  Scimatco  optical  pyrometer.  Portions  of  aluminum  oxide  were  re- 
moved at  815,  900,  980,  1065,  and  1150  degrees  C.  Solubility  tests 
were  made  by  taking  1  gram  of  each  portion  and  digesting  for  one 
hour  with  100  cc.  hydrochloric  acid  (1:1),  filtering,  and  determining 
A1203  in  the  nitrate. 

Portion  heated  to      815°C.  900°C.  980°C.  1065°C.  1150°C. 
Gram  soluble  A1203  0.9317  0.3962  0.2337  0.0472     0.0390. 

The  increase  in  temperature  was  at  the  rate  of  8  to  10  minutes 
between  observations.  Another  portion  of  the  same  A^Os  prepared 
above,  was  placed  in  a  boat  in  the  silica  tube  of  an  electric  furnace 
and  held  for  one  hour  at  a  temperature  of  1000°C.;  one  gram  of  this 

1  Metallurgical  and.  Chemical  Engineering,  Dec.  1,  1915. 


76  ALUMINUM 

was  treated  as  above  with  1 :1  hydrochloric  acid  and  showed  0.0285 
gram  soluble  Ala Os.  One  gram  alimdum,  120  mesh,  was  treated  with 
hydrochloric  acid  as  above  and  showed  a  mere  trace  of  soluble  Al 2 Os. 

The  solubility  diminishes  with  increase  of  temperature  and  length 
of  time  to  which  the  Ala Os  had  been  exposed  to  the  heat.  If  AlzOg 
exposed  to  1000°C,  will  yield  2.85  per  cent  of  its  A1203  content,  and 
alundum  exposed  to  a  little  over  2000°C.  yields  a  trace,  it  is  safe  to 
assume  that  the  A^Os  formed  in  molten  steel  would  yield  only  1  or  2 
per  cent  of  its  content  on  treatment  with  dilute  hydrochloric  acid, 
which  on  such  low  figures  as  obtain  with  percentages  of  A^Os  in  steel 
is  certainly  negligible. 

The  above  assertion  has  been  borne  out  in  practice,  by  adding 
just  enough  aluminum  to  deoxidize  the  steel,  avoiding  an  excess. 
By  employing  the  method  as  given  below  on  such  steels,  all  of  the 
aluminum  was  found  to  be  in  the  insoluble  residue  as  oxide. 

The  method  is  as  follows: 

Dissolve  50  grams  drillings  in  a  mixture  of  200  cc.  strong  hydro- 
chloric acid  and  300  cc.  water  at  gentle  heat,  bring  to  a  boil,  allow  in- 
soluble matter  to  settle  and  filter  through  a  double  Baker  &  Adamson 
grade  A  paper  or  Schleicher  &  Schull  No.  590,  and  wash  with  hot 
dilute  (1 :2)  hydrochloric  acid  and  hot  water.  Ignite  the  residue  in 
a  platinum  fusion  crucible.  Add  Yi  gram  pure  sodium  borate2 
calcined,  and  heat  gently  a  few  minutes  till  A^Os  is  in  solution.  Now 
add  5  grams  pure  sodium  carbonate  and  fuse  a  few  minutes  longer 
until  all  is  melted  and  in  a  state  of  quiet  fusion.  Dissolve  fusion  in 
hot  water  in  a  platinum  or  nickel  dish,  and  determine  AlaOa  in  the 
usual  manner. 

In  the  nitrate  the  Al  is  directly  precipitated  as  phosphate  accord- 
ing to  Wohler,  as  described  by  Blair.  The  precipitate  is  dissolved  in 
HNOs,  and  chromium  oxidized  by  boiling  with  KMnOi,  and  theAl 
precipitated  from  the  Cr,  Cu,  etc.,  with  ammonia.  This  precipitate 
is  dissolved  in  HC1  evaporated  to  dryness  to  separate  SiC>2,  and  in 
the  filtrate  the  Al  is  again  precipitated  as  phosphate  as  before. 

2  It  is  generally  impossible  to  decompose  all  the  A1203  by  a  sodium  carbonate  fusion  alone. 


ARSENIC  77 


DETERMINATION  OF  ARSENIC 
DISTILLATION  METHOD 

Very  good  results  can  be  obtained  by  the  Distillation  Method 
in  determining  arsenic  in  iron  and  steel.  The  methods  used  in  the 
determination  of  this  element  require  the  use  of  either  ferrous  sulphate 
or  cuprous  chloride.  We  prefer  the  latter. 

The  method  used  in  our  laboratory  has  been  carefully  worked  out 
and  has  been  found  to  give  very  satisfactory  results.  The  essential 
details  being  as  follows: 

Dissolve  20  grams  of  drillings  in  a  6  inch  diameter  casserole,  using 
300  cc.  of  nitric  acid  (1.20  Sp.  Gr.).  Heat  slowly  in  order  to  prevent 
the  reaction  from  becoming  too  violent.  Evaporate  to  dryness  on 
hot-plate  and  bake  until  no  more  nitrous  fumes  are  evolved.  Remove 
from  hot  plate  and  allow  to  cool,  transfer  the  ferric  oxide  to  distillation 
flask  to  which  is  attached  a  50  cc.  pipette  which  dips  into  a  beaker  con- 
taining 200  cc  of.  distilled  water.  Place  in  distillation  flask  40  grams 
of  cuprous  chloride  and  300  cc.  of  concentrated  hydrochloric  acid, 
boil  until  about  two-thirds  of  the  hydrochloric  acid  has  distilled  over. 

From  the  beginning  of  the  distillation  pass  hydrogen  sulphide  gas 
into  the  distillate  while  same  is  being  heated  almost  to  the  boiling  point 
with  the  use  of  a  small  electric  hot-plate.  This  will  insure  a  rapid  pre- 
cipitation of  arsenious  sulphide  which  settles  readily  and  can  be  easily 
filtered.  After  the  distillation  is  discontinued  remove  the  beaker 
containing  the  distillate  from  the  source  of  heat,  dilute  to  500  cc.  with 
cold  water  and  continue  to  pass  hydrogen  sulphide  gas  into  the  solution 
until  cold.  Disconnect  pipette  and  rinse  inside  and  outside  with  two 
or  three  cc.  of  concentrated  ammonia,  allowing  washings  to  run  into 
beaker  containing  arsenious  sulphide. 

Allow  the  precipitate  to  settle  and  filter  on  asbestos  using  a 
Gooch  crucible,  w^ash  with  distilled  water  until  free  from  acid.  Trans- 
fer the  asbestos  felt  containing  the  arsenious  sulphide  to  a  250  cc. 
beaker.  Add  10  cc.  of  fuming  nitric  acid  or  10  cc.  of  nitric  acid  (1.42 
Sp.  Gr.)  and  1  gram  of  potassium  chlorate.  Evaporate  to  dryness. 
Dissolve  the  arsenic  acid  in  dilute  hydrochloric  acid,  filter  and  wash 
with  hot  distilled  water.  Concentrate  to  about  20  cc.,  heat  to  boiling 


78  ARSENIC 

and  add  10  cc.  of  magnesia  mixture,  and  10  cc.  of  ammonia  (0.95  Sp.Gr.) 
Continue  to  boil  for  15  minutes,  remove  from  the  source  of  heat,  add 
20  cc.  of  alcohol  and  let  stand  for  5  hours.  Filter  and  wash  the  pre- 
cipitate on  a  weighed  Gooch  crucible,  dry,  ignite  and  weigh  as  mag- 
nesium pyroarsenate  which  contains  48.27%  arsenic. 

Magnesia  Mixture 

Dissolve  110  grams  of  crystallized  magnesium  chloride  in  a  small 
amount  of  water.  Add  140  grams  of  ammonium  chloride,  make  dis- 
tinctly ammoniacal  with  ammonia,  and  dilute  to  2000  cc.  with  dis- 
tilled water.  Allow  the  solution  to  stand  and  siphon  off  the  clear 
solution  for  use. 


BORON  79 


THE  DETERMINATION  OF  BORON  *} 

After  considerable  experimenting  with  various  methods  suggested 
for  the  determination  of  boron  in  metallurgical  products,  we  have 
found  the  following  plan  to  be  both  accurate  and  rapid: 

Fuse  one-half  gram  of  the  powdered  sample  with  potassium 
nitrate  and  sodium  carbonate  in  a  platinum  crucible.  Pour  the  melt 
upon  an  iron  plate,  transfer  with  the  crucible  to  a  porcelain  dish  and 
boil  with  just  enough  water  to  effect  disintegration.  Add  a  little 
sodium  peroxide  during  the  boiling  to  precipitate  manganese.  Filter 
into  an  Erlenmeyer  flask  and  wash  with  hot  water.  Reserve  the 
residue  for  manganese  determination. 

Acidify  the  filtrate  with  hydrochloric  acid  and  then  add  a  moderate 
excess  of  calcium  carbonate.  Connect  the  flask  with  an  upright  re- 
flux condenser  and  boil  about  ten  minutes  to  remove  all  carbon  dioxide. 
Filter,  cool  to  room  temperature,  add  phenolphthalein  and  run  in 
N/10  sodium  hydrate  to  pink  color;  then  add  about  one  gram  man- 
nite.  This  destroys  the  color,  and  more  sodium  hydrate  is  added 
until  the  color  is  permanent,  even  on  the  addition  of  more  mannite. 

One  cc.  N/10  sodium  hydrate  equals  .0011  gram  boron.  No 
deduction  is  required  for  blank. 

One-half  gram  steel  containing  4  per  cent,  manganese  to  which 
.03  gram  boron  was  added  in  the  form  of  fused  boric  acid  gave  by  this 
method  .0299  gram  boron. 

Dissolve  residue  from  the  fusion  in  hydrochloric  acid,  add  15  cc. 
sulphuric  acid  and  evaporate  to  strong  sulphuric  fumes.  Cool, 
dilute,  heat  till  clear  and  make  up  to  250  cc.  Take  50  cc.  for  manga- 
nese determination  by  the  bismuthate  method,  and  50  to  100  cc  for 
iron  determination.  Manganese  may  be  determined  on  a  separate 
sample  if  desired  by  the  bismuthate  method  without  separating  the 
boron. 

Silica  is  determined  in  the  usual  way,  and  carbon  by  direct  ignition 
in  oxygen,  spreading  the  sample  over  ignited  asbestos  in  the  combustion 
boat. 


80 


BORON 


CARBON  81 


DETERMINATION  OF  CARBON 
COLORIMETRIC   METHOD 

In  determining  carbon  by  color  it  is  essential  that  the  standard 
contain  approximately  the  same  percentage  of  carbon  as  the  sample, 
and  also  that  the  materials  have  had  the  same  heat  treatment.  For 
the  analysis  of  pure  iron  we  furnish  free  a  vial  of  standardized  American 
Ingot  Iron. 

Dissolve  .5  gram  of  the  sample  and  .5  gram  of  the  standard  in 
10  cc.  of  nitric  acid,  (1.18  Sp.  Gr.),  using  10  in.  by  1  in.  test  tubes,  heat 
over  a  Bunsen  flame  until  the  metal  is  dissolved  and  tubes  are  free 
from  brown  fumes.  Cool  gradually  and  pour  into  carbon  comparison 
tubes,  dilute  standard  with  distilled  water  to  at  least  20  cc.  (depending 
upon  the  carbon  content)  and  add  water  to  tube  containing  sample 
until  colors  match.  The  percentage  of  carbon  present  is  determined 
by  the  following  formula: 

cc.  of  Standard  :  cc.  of  Sample  ::  percentage  of  Carbon  in 
Standard  :  X. 


82 


CARBON 


CARBON  83 

DETERMINATION  OF  CARBON  BY  COMBUSTION 

The  determination  of  carbon  in  iron  and  steel  is  made  by  direct 
combustion,  using  a  %  inch  bore  x  30  inch  silica  tube  heated  in  an 
electric  furnace.  A  temperature  of  1000  to  1030°  C.,  is  maintained 
with  the  use  of  a  rheostat.  The  apparatus  being  standardized  oc- 
casionally with  the  use  of  a  platinum,  platinum-rhodium  platinum- 
rhodium  thermo  couple. 

We  have  found  that  a  gas  furnace  is  not  reliable  where  the  gas 
pressure  fluctuates  considerably.  This  is  due  to  the  danger  of  over- 
heating and  causing  devitrification  of  the  silica  tube,  rendering  it 
porous  and  the  results  obtained  unreliable. 

The  following  method  has  been  found  to  be  extremely  accurate 
when  dealing  with  traces  of  carbon  such  as  exist  in  American  Ingot 
Iron.  The  method  we  employ  is  essentially  as  follows: 

Use  a  platinum  or  nickel  boat  approximately  G'^/^'x/^",  on 
which  place  a  Y%"  layer  of  60  or  90-mesh  alundum,  free  from  carbon 
and  alkalies,  which  has  been  heated  to  1000°  C.,  before  being  used  for 
the  first  time.  Make  a  channel  in  the  alundum  and  place  therein  4 
grams  of  low  carbon  steel  or  American  Ingot  Iron,  in  the  form  of  fine 
drillings.  Spread  compactly  and  evenly,  then  cover  the  borings  with 
alundum. 

Connect  a  Meyer  bulb  containing  75  cc.  of  clear  barium  hy- 
droxide solution  (30  grams  Ba(OH)2  '  8H2.  O,  in  1  liter  of  water) 
direct  with  the  silica  tube. 

Insert  the  boat  containing  the  drillings  into  the  central  portion 
of  the  silica  tube  and  quickly  connect  with  the  source  of  purified 
oxygen  which  is  passed  into  the  apparatus  at  the  rate  of  not  more  than 
100  cc.  per  minute,  continuing  the  operation  for  20  minutes.  The 
flow  of  oxygen  gas  is  regulated  with  the  use  of  a  high  pressure  reducing 
valve  which  will  maintain  a  uniform  rate  of  flow. 

The  Meyer  bulb  is  disconnected,  the  solution  filtered  and  washed 
with  boiled  distilled  water.  Care  should  be  taken  to  filter  under 
conditions  which  will  prevent  contamination  by  any  carbon  dioxide 
which  may  be  formed  within  the  laboratory. 

The  filter  paper  containing  the  barium  carbonate  is  placed  in  a 
platinum  crucible  and  ignited  at  a  low  temperature  until  all  volatile 
matter  has  been  driven  off,  and  finish  at  a  red  heat  until  all  carbon 
from  the  paper  has  been  consumed. 


84  CARBON 

The  barium  carbonate  is  weighed,  multiplied  by  6.08  and  divided 
by  the  weight  taken,  which  will  give  percentage  of  carbon. 

For  the  analysis  of  high  carbon  steel  we  employ  the  rapid  method 
in  which  we  take  1/^-grams,  and  absorb  the  carbon  dioxide  in  soda 
lime  contained  in  a  Fleming  bulb.  A  complete  determination  can 
be  made  in  less  than  seven  minutes. 


IRON  YARNING  TOOL  FOUND  UNDER  WATER  MAINS 

AT  CINCINNATI,  OHIO. 

BURIED  IN  THE  GROUND  ABOUT  51  YEARS 
TEST  NO,  4524          FILE  1O3 

Sulphur  .030 

Phosphorus  .030 

Carbon  .015 

Manganese  .112 

Copper  .080 

Silicon  .027 

Oxygen  .050 

Nitrogen  .004 


CARBON  85 

CARBON  IN  IRON  1 

By  T.  D.  YENSEN.  2 

It  has  long  been  known  that  carbon  has  a  great  influence  upon 
the  properties  of  iron  and  iron  alloys.  On  account  of  the  small 
quantities  of  carbon  involved — 0.1  per  cent  being  regarded  as  a  medium 
carbon  steel — and  the  presence  of  carbonaceous  matter  in  almost 
everything  that  is  used  in  making  chemical  analyses,  the  correct  de- 
termination of  carbon  in  iron  is  the  most  difficult  problem  in  iron  and 
steel  analysis.  Not  only  are  the  total  quantities  of  carbon  very  small, 
but  carbon  may  exist  in  iron  in  various  forms,  one  or  more  of  which 
may  influence  the  properties  considerably,  while  others  may  have 
little  or  no  influence  upon  these  properties.  The  accurate  determina- 
tion of  these  small  quantities  and  the  separation  of  the  different  forms 
is,  therefore,  of  great  importance,  and  a  large  amount  of  work  has  been 
done  lately  to  discover  suitable  methods  to  accomplish  this  purpose. 

In  another  paper,  Mr.  C.  J.  Rottman  is  giving  an  account  of  the 
various  methods  that  have  been  and  are  being  used  for  the  determina- 
tion of  carbon  in  iron  and  steel.  He  is  also  describing  certain  im- 
provements in  the  method  of  analysis  in  connection  with  the  com- 
bustion method — particularly  in  regard  to  absorbing  the  CO2 — 
improvements  that  greatly  diminish  the  errors  in  the  analysis.  How- 
ever, even  these  improvements  were  not  considered  sufficient.  The 
method  described  in  this  paper  is  a  combustion  method,  but  it  elimi- 
nates some  of  the  most  important  sources  of  error  inherent  in  the 
standard  method,  namely  those  due  to  absorption  and  weighing,  and 
makes  it  possible  to  decide  accurately  whether  all  the  carbon  has  been 
burnt  out  of  the  sample. 

The  standard  method  consists  in  heating  the  sample — in  the 
form  of  shavings  or  chips — in  a  gas-tight  tube  to  a  temperature  of 
800  to  1000  C.,  passing  oxygen  through  the  tube  and  absorbing  the 
resulting  CO2  in  a  bulb  containing  KOH  or  the  equivalent.  The 
increase  in  weight  of  the  KOH  bulb  gives  the  weight  of  CO2.  Pre- 
cautions are  taken,  of  course,  so  that  presumably  nothing  but  the 
CO2  from  the  sample  is  absorbed  by  the  KOH  bulb.  As  ordinarily 
practiced  this  method  is  satisfactory  for  carbon  content  of  0.1  per 
cent,  or  more,  and  if  great  care  is  exercised  the  error  should  be  within 
±0.01  per  cent.  Mr.  Rottmann  states  that  with  his  improvements 
he  is  able  to  get  an  accuracy  of  ±0.002  per  cent.  While  this  may  be 
correct  when  the  analysis  is  done  with  painstaking  care,  it  is  very 

1  Transactions  American  Electro  Chemical  Society,  April   1920. 

2  Westinghouse  Research  Laboratory,  East  Pittsburgh,  Pa. 


86  CARBON 

doubtful  if  better  than  d=  0.01  can  be  obtained  with  the  analysis  in 
the  hands  of  a  regular  analytical  chemist. 

Errors  in  the  Present  Method 

The  chief  sources  of  error  in  the  present  method  are: 

1.  Contamination  of  sample  due  to  oil,  grease,  dust  or  dirt  of 
any  kind. 

2.  Dust  or  dirt  or  other  carbonaceous  matter  in  the  combustion 
tube,  in  the  sample  holder,  or  in  the  connections  between  the  tube  and 
the  rest  of  the  apparatus. 

3.  Adsorbed  CO  or  CO2  in  the  walls  of  the  combustion  tube,  or 
in  the  sample  holder. 

4.  Admission  of  CO  or  CO2  in  opening  the  combustion  tube. 

5.  Incomplete  washing  of  the  oxygen  before  it  enters  the  com- 
bustion tube. 

6.  Incomplete  oxydation  of  the  carbon,  resulting  in  some  CO 
instead  of  all  CO2. 

7.  Incomplete  absorption  of  CO2  in  the  KOH  bulb. 

8.  Weighing  of  the  KOH  bulb;    moisture  and  dust  collects  on 
the  bulb  in  uncertain  amounts,  and  the  weighing  itself  can  at  best  be 
done  with  an  accuracy  of  ±0.1  mg. 

9.  Carbon  left  in  sample. 

Some  of  these  sources  of  error  can  be  eliminated  in  the  present 
method  by  careful  manipulation,  thus 

(1)  can  largely  be  taken  care  of  by  careful  sampling  and  boiling 
the  sample  in  ether  prior  to  placing  it  in  the  combustion  boat. 

(2)  and   (3)  can  be  minimized  by  burning  out  the  system,  in- 
cluding the  sample  holder,  with  oxygen,  prior  to  introducing  the  sam- 
ple, while 

(5)  can  be  easily  eliminated  by  means  of  active  KOH  and  soda- 
lime  in  the  train,  according  to  standard  practice. 

This  leaves  (4),  (6),  (7),  (8)  and  (9)  as  sources  of  error  that  can 
not  readily  be  eliminated  when  the  present  method  is  used.  The 
resulting  errors  vary  to  such  an  extent  that  it  is  difficult  to  get  satisfac- 
tory blanks,  and  it  is,  therefore,  necessaryto  make  radical  modifications. 


CARBON 


87 


Mr.  Ryder's  Results 

Mr.  H.  M.  Ryder  has  done  a  great  deal  of  work  on  the  elimination 
-of  gases  from  metals,  including  iron  and  iron-silicon  alloys,  by  heating 
the  samples  in  vacuo  and  analyzing  the  gases  given  off.3  It  was  found 
that  large  quantities  of  CO  and  CO2  were  given  off  below  600°  C., 
whereas  additional  CO  was  given  off  in  varying  amounts,  depending 
upon  the  alloy,  at  and  above  the  A2  transformation  point. 

Based  on  these  results  it  was  concluded  that  the  CO  and  CO2 
given  off  below  600°  exist  in  the  metal  as  adsorbed  gases  while  the 
CO  given  off  at  and  above  A2  is  due  to  chemical  reaction  between  the 
combined  or  graphitic  carbon  in  the  metal  and  the  iron  oxide  present. 

It  is  quite  probable  that  these  different  forms  of  carbon,  i.  e.,  that 
existing  as  adsorbed  gases  and  that  existing  as  combined  or  graphitic 
carbon,  have  different  effects  upon  the  physical  properties  of  the 
metal  and  it  is,  therefore,  of  great  importance  to  differentiate  between 
them.  This  differentiation  is  taken  care  of  in  the  new  method  as 
described  below. 

The  New  Method 

A  sketch  of  the  apparatus  is  shown  on  Page  88,  and  is  self  explana- 
tory. The  following  is  a  condensed  statement  of  the  procedure: 

(a)  Preparation  of  the  Sample) . 

The  sample  is  carefully  collected  to  keep  out 
foreign  matter  and  the  weighed  portion  then  ** 
cleaned  with  ether  in  the  apparatus  shown  on 
Page  87.  The  ether  is  evaporated  in  an  Erlen- 
meyer  flask  and  the  vapor  passed  through  the 
sample  held  in  the  Gooch  crucible.  The  con- 
densed vapor  again  passes  through  the  sample 
on  its  way  from  the  condenser  to  the  bottom 
of  the  flask  and  is  reheated  by  the  rising  vapors. 
The  sample  is  thus  exposed  to  a  constant  stream 
of  hot,  clean  ether,  carrying  oily  and  greasy 
matter  down  into  the  bottom  of  the  flask.  This 
procedure  should  minimize  source  of  error  No.  1.  Apparatus  for  cleaning 

Sample. 

(b)  Preparation  of  Combustion  Boat  and  Tube. 

The  sample  is  then  placed  on  a  layer  of  specially  prepared  alundum 
in  an  alundum  combustion  boat  that  has  previously  been  heated  in  the 
combustion  tube  to  1000°  in  a  stream  of  oxygen.  The  sample  is  also 
covered  with  a  layer  of  alundum.  This  precaution  should  eliminate 

3  H.  M.  Ryder:  "A  Precision  Method  for  the  Determination  of  Gases  in  Metals. "Trans.  Am. 
Electrochem.  Soc.  (1918),  33,  197.  "Analysis  of  Small  Quantities  of  Gases."  Jour.  Am.  Chem. 
Soc.  (1918),  40,  No.  11,  1656. 


<?'<*.;  t/t. 


88 


CARBON 


carbonaceous  matter  in  the  boat  and  in  the  combustion  tube  (sources 
of  error  No.  2  and  No.  3). 

(c)  Elimination  of  CO  and  C02  Introduced  into  Tube  while  Open. 

The  combustion  boat  is  now  placed  near  the  center  of  the  tube 
with  the  furnaces  moved  over  to  one  end,  and  the  tube  is  closed. 
With  the  boat  at  room  temperature  or  slightly  above,  the  tube  is 
evacuated  to  a  pressure  of  0.01  mm.  Hg  or  better,  eliminating  all  but 
traces  of  the  free  gases  present  in  the  system,  thus  eliminating  source 
of  error  No.  4. 

(d)  Determination  of  Adsorbed  CO  and  CO  2. 

At  the  end  of  the  above  preliminary  vacuum  treatment,  liquid 
air  is  placed  on  the  trap  and  the  600°  furnace  is  moved  over  the 
sample.  The  sample  is  treated  at  600°  in  vacuum  for  15  minutes 
or  more,  in  order  to  remove  the  adsorbed  gases.  The  CO2  is  "frozen 
out"  in  the  liquid  air  trap  and  the  amount  determined  by  isolating  the 
analyzing  apparatus,  allowing  the  CO2  to  evaporate,  and  jioting •  the 
increase  in  pressure. 


Apparatus  for  Carbon  Determination. 

(e)  Final  Combustion. 

During  the  analysis  of  the  CO2  under  (d),  oxygen  is  admitted  to 
the  combustion  tube  up  to  atmospheric  pressure  through  the  CaCl2 
and  soda-lime  bulbs  to  wash  it  free  from  H2O  and  CO2,  the  flow  being 
regulated  by  means  of  the  stop  cock  and  regulator.  This  filling  of 
the  combustion  tube  requires  about  10  minutes,  and  at  the  end  of  this 
period  the  previous  analysis  is  completed  and  the  combustion  tube  is 
evacuated  through  the  CO2— snow  and  liquid  air  traps.  When  the 
pressure  reaches  0.01  mm.  Hg  cut  off  A  is  closed,  the  system  further 
evacuated  to  0.001  mm.  and  the  CO2  analyzed  as  before,  at  the  same 
time  filling  the  combustion  tube  a  second  time  with  oxygen  to  make 
another  analysis  to  make  sure  that  all  the  carbon  has  been  removed. 


CARBON  89 

Complete  combustion  of  the  carbon  is  insured  by  passing  the 
gases  through  CuO  heated  to  400°,  eliminating  source  of  error  No.  6. 

From  the  volume  of  the  apparatus  and  the  pressure,  the  amount 
of  carbon  can  then  be  calculated.  Absorption  of  CO2  by  KOH  and 
weighing  is  thus  done  away  with  altogether,  eliminating  sources  of 
error  No.  7  and  No.  8. 

If  there  is  any  reason  to  believe  that  all  the  carbon  has  not  been 
burnt  during  the  previous  combustion  periods,  the  combustion  process 
can  be  repeated  any  number  of  times  until  no  further  CC>2  is  obtained. 
This  can  be  done  without  introducing  additional  errors,  which  is  not 
the  case  when  the  ordinary  combustion  method  is  used.  Source  of 
error  No.  9  is  thus  eliminated. 

Details  of  Apparatus 

(a)  Furnaces. 

The  1000°  furnace  is  a  platinum-wound  furnace  with  a  porce- 
lain tube  24  in.  (60  cm.)  long  and  1/4  in.  (4.4  cm.)  bore,  insulated 
with  fire  clay  and  sil-o-cel.  It  can  be  maintained  at  1000°  with  an 
input  of  1  kw.,  and  at  1400°  with  3  kw. 

The  600°  furnace  is  12  in.  (30  cm.)  long,  \%  in.  (4.4  cm.)  bore, 
consists  of  a  silica  tube  wound  with  nichrome  ribbon  and  insulated 
by  means  of  magnesia  pipe  covering. 

(b)  Quartz  Tube. 

The  quartz  tube  is  1%  in.  (3.5  cm.)  inside  by  liMi  in.  (4.1  cm.) 
outside  diameter  by  6  ft.  (180  cm.)  long.  One  end  is  permanently 
sealed  with  a  glass  cap  and  cement,  while  the  other  end  is  provided 
with  a  ground  glass  joint. 

(c)  The  CuO  Tube. 

The  CuO  tube  is  a  Pyrex  glass  tube  %  in.  (1.6  cm.)  diameter, 
wound  with  asbestos  and  nichrome  ribbon,  without  any  heat  insulation 
on  the  outside.  It  is  filled  with  fine  copper  wire  and  heated  to  400°. 

(d)  Connections. 

All  connections  between  the  different  parts  of  the  apparatus  are 
made  with  sealed  hard  glass  tubing,  eliminating  sources  of  error  due 
to  leaks. 


90 


CARBON 


(e)  Analyzing  Apparatus. 

The  analyzing  apparatus  was  constructed  in  accordance  with  a 
design  originated  by  Mr.  Ryder.  A  sketch  of  same  is  shown  on  Page  90. 
The  apparatus  is  made  from  hard  glass  throughout.  The  sketch 
shows  the  mercury  in  the  cutoffs  in  position  ready  for  analyzing  the 
CO2  frozen  out  in  the  liquid  air  trap.  The  volume  then  includes  the 
trap,  the  bulb  of  the  McLeod  gage  and  the  connecting  tubing.  Up  to 
the  zero  points  of  the  mercury  column  the  volume  is  259  cc.  As  the 
pressure  increases,  the  mercury  falls  in  the  various  cut-offs,  thus  in- 
creasing the  volume  of  the  system.  The  volume,  being  a  function  of 
the  pressure,  was  consequently  determined  for  various  pressures  by 
means  of  the  auxiliary  bulb.  The  relation  between  the  pressure  and 
the  carbon  is  shown  graphically  on  Page  91.  Expressed  in  an  equation 
this  relationship  is: 

C  =  (0.168  +  0.000095  P)  P,  where  C  =  mg.  of  carbon  and  P  = 
pressure  in  mm.  Hg.  Pressures  up  to  2  mm.  are  measured  on  the 
McLeod  gage,  while  higher  pressures  are  measured  by  means  of  the 
difference  in  level  of  the  mercury  columns  of  the  mercury  pump  cut-off. 


ftu,.  Bu/t  fir  C*Mr  An*/.  Sys/en. 


Analyzing  Apparatus  for  Carbon  Determination. 


CARBON 


91 


Pressures  can  be  measured  on  the  McLeod  gage  with  an  accuracy  of 
±0.01  mm.  Hg,  and  from  the  above  equation  it  will  be  seen  that  this 
corresponds  to  a  carbon  content  of  ±0.00168  mg.  or  ±0.0000168 
percent  carbon  if  a  10  g.  sample  is  used.  This  is  far  beyond  the 
required  accuracy,  so  that  no  difficulty  will  be  had  in  eliminating 
sources  of  error  No.  7  and  No.  8. 

(/)  Diffusion  Pump. 

The  pump  was  constructed  in  accordance  with  the  design  de- 
veloped by  Mr.  J.  E.  Shrader,4  and  is  of  the  type  that  can  be  operated 
at  fairly  high  backing  pressures.  It  is  capable  of  evacuating  the 
system  down  to  0.0001  mm.  Hg  in  5  minutes. 

Preliminary  Tests 

Numerous  preliminary  tests  were  made  to  weed  out  the  weak 
points  of  the  apparatus  and  to  determine  the  limits  of  accuracy. 


%*>' 

\     A 

OfS 

/I  Ce 

^ 

^^•x 

^ 

r 

/? 

r'' 

^ 

I/1L+I 

^ 

'    N, 

'//fl 

it 

/ 

','jk 

^ 

^* 

t'/t 

7 

/;; 

w 

<h 

)  

-a-c 

Y// 

£  0.30 

!k 

.-—  1 

V 

\ 

'h 

•$„„, 

j 

n  is 

It 

i 

fl/fl 

nk 

/ 

^^ 

I 

i  

c 

)  ••• 

•  — 

C 

7      1 

0      2. 

*      Jt 

?      4 

0 

O      10     20     30     40     £-0     to     70 
ff/n. +f  JOO6*  ,'»  0*. 

Carbon  in  Electrolytic  Iron.     Standard  Sample. 

4  Westinghouse  Research  Laboratory.       See  Phys.  Rev.  N.  S.,  Vol.  12,  No.  1,  July,  1918. 


92 


CARBON 


1 .  To  determine  the  effectiveness  of  the  various  absorbing  agen ts, 
a  number  of  tests  were  made  with  ordinary  air  passing  through  properly 
prepared  bulbs  at  a  rate  of  120  cc.  per  minute  for  15  minutes,  making  a 
total  of  1800  cc.  The  CO2  escaping  the  first  bulb  was  frozen  out  by 
liquid  air  in  the  analyzing  system  and  the  amount  determined  as 
usual.  The  result  is  shown  in  Table  I. 


Table  I 
Efficiency  of  Various  Absorbing  Agents  for  C02 


No. 

Absorbing  Agent 

Amount  CO2  in  1800 
c.c.  Air  not  Absorbed 
by  Absorb.  Agent 
mg. 

Efficiency  of 
Absorb.  Agent 
Percent 

1 

None                                                    .  . 

0.840 

0 

2 

KOH  and  Ca  C12 

0.350 

60 

3 

Fleming  Bulb  (Soda  lime)  

0.025 

97 

4. 
5. 
6. 

Liquid  Air,  Plain  Trap  
Same,  Trap  filled  with  Glass  Wool  . 
Same,  Trap  filled  with  Steel  Wool.  . 

0.025 
0.001 
0.001 

97 
99.9 
99  9 

This  shows  that  the  rate  used  was  too  high  for  the  KOH  bulb 
but  safe  for  the  Fleming  bulb.  The  plain  liquid  air  trap  passed 
3  percent  of  the  CO2,  while  the  traps  filled  with  steel  or  glass  wool 
passed  only  0.1  percent  of  the  total  CO2.  Hence  the  adoption  of  the 
glass  wool  trap  for  the  analyzing  system. 

2.  A  glass  wool  filled  liquid  air  trap  was  at  first  also  used  in  the 
purifying  train,  but  it  was  found  that  the  suction  of  this  trap  on  the 
CO2   given  off  in  the  furnace  during  the  passage  of  this  oxygen  was 
sufficient  to  freeze  out  from  10  to  30  percent  of  the  CO2  given  off. 
Furthermore,  the  liquid  air  trap  in  the  purifying  train  necessitated 
passing  oxygen  through  the  furnace  and  the  trap  at  a  reduced  pressure 
in  order  to  keep  the  oxygen  from  liquifying  in  the  trap.       These  con- 
siderations led  to  the  adoption  of  the  Fleming  bulb  for  the  purifying 
train.      Tafjle  I  shows  that  this  bulb  allows  only  3  percent  of  the  total 
CO2  in  the  oxygen  to  pass  through,  and  as  the  amount  of  CO2  in  the 
oxygen  is  very  small  (only  0.02  mg.  per  1800  c.  c.  as  compared  to 
0.84  mg.  for  air)  it  is  evident  that  the   Fleming  bulb   is   sufficiently 
effective. 

3.  Asbestos  plugs  were  originally  used  at  the  exit  end  of  the 
combustion  tube  to  protect  the  wax  seal  from  undue  heating  and  no 
protection  was  used  at  all  at  the  entrance  end,  where  De  Kotinsky 


CARBON  93 

cement  was  used  to  seal  the  glass  to  the  quartz  tube.  It  was  soon 
found  however  that  this  arrangement  caused  a  great  deal  of  trouble, 
and  the  arrangement  as  finally  adopted  is  shown  on  Page  93.  The  pro- 
tecting bulbs  at  the  ends  consist  of  Pyrex  glass  filled  with  asbestos, 
evacuated  and  sealed  off.  They  are  securely  held  in  place  so  that 
they  cannot  be  drawn  into  the  heated  portion  of  the  tube.  They 
prevent  heating  of  the  wax  very  effectively  without  the  use  of  materials 
in  the  combustion  tube  that  absorb  and  give  off  gases  in  considerable 
and  uncertain  amounts. 


GrcunJ  S/oss  Joint  Pyrtx  Gltss  Bv/ifS,  Aittsfot /,//>/  t- 


Combustion  Tubes. 

4.  Originally  the  house  vacuum  was  used  to  evacuate  the  furnace 
down  to  a  pressure  of  about  10  mm.  Hg.  The  house  vacuum  was 
then  cut  off  and  the  final  evacuation  done  with  a  diffusion  pump. 
However,  large  variations  in  the  blanks  (from  0.0005  mg.  to  0.05  mg.) 
led  to  investigating  the  house  vacuum  system  as  a  source  of  CO2. 
The  house  vacuum — as  the  name  implies — is  used  by  the  whole 
laboratory,  and  consequently  there  is  a  large  variation  in  the  pressure, 
ranging  from  a  few  mm.  to  2  or  3  cm.  Hg  when  someone  is  evacuating 
a  large  volume.  It  is  conceivable  that  a  sudden  increase  in  the  line 
pressure  may  cause  a  reverse  current  into  the  analyzing  system  and  if 
there  is  any  CO2  in  the  line  this  will  be  frozen  out  in  the  liquid  air  trap. 
It  was  consequently  decided  to  do  all  evacuation  with  the  backing  pump 
for  the  diffusion  pump,  and  this  resulted  in  a  decided  improvement. 
The  apparatus  in  its  final  shape  is  therefore  as  shown  on  Pages  88  and 
93,  using  an  individual  pump  for  the  evacuation. 

* 
With  the  furnaces  cold  and  with  no  sample  in  the  boat,  but 

otherwise  running  the  apparatus  as  usual,  the  amount  of  C  obtained 
is  only  0.002  mg.  (with  a  variation  of  from  0.001  to  0.003  mg.). 


94 


METALLURGICAL  CONTROL 


With  the  furnaces  heated  as  usual  (to  600  and  to  1000°  C.  re- 
spectively) and  going  through  the  regular  procedure  of  analyzing  a 
sample  except  that  no  sample  is  used,  the  following  results  are  typical. 

Table  II 

Blanks  of  Apparatus 
Procedure  same  as  usual,  except  no  Sample  in  Boat. 


Test 
No. 

Tube  Evac. 
Boat  Cold 

Boat  heated  in 
Vacuoto600J 

Boat  heated  to  and  at  1000° 
Tube  filled  with  O3,  then  evacuated. 

104 
108 
124 

Mean  o 
Variatio 

min. 

Final 
Pres. 
sure 

mm. 

min. 

Final 
Pres. 
sure 

mm. 

Carb. 
Obt'd 

mg. 

1st  Period 

2nd  Period 

min. 

Final 
Pres- 
sure 
mm. 

Carb. 
Obt'd 
mg. 

min. 

Final 
Pres- 
sure 
mm. 

Carb. 
Obt'd 
mg. 

23 
14 
51 

F  3Te 
n  fron 

0.010 
0.015 
0.002 

sts 

i  Mean 

11 
20 
20 

0.000 
0.003 
0.001 

0.013 
0.027 
0.017 

0.019 
±0.007 

27 
26 
36 

0.010 
0.010 
0.005 

0.029 
0.025 
0.038 

0.031 
±0.007 

25 
40 

o'.oio 

0.005 

0'.030 
0.044 

0.037 
±0.007 

The  maximum  variation  in  the  blank  is  therefore  less  than 
d=0.010  mg.  C,  which  for  a  10  g.  sample  amounts  to  ±0.0001  per  cent. 
For  samples  of  different  carbon  contents  the  probable  errors  in  the 
analysis  are  therefore  as  follows: 

Table  III 

Probable  Errors  in  Samples  of  Various  Carbon  Contents. 
10  g.  Samples. 


Carbon  Contents 

Errors  in  Analysis 

Percent 

Mg. 

Mg.  (±) 

Percent  (.  ) 

0.1000 

10 

0.01 

-       0.1 

0.0100 

1 

0.01 

1.0 

0.0010 

0.1 

0.01 

10.0 

0.0001 

0.01 

0.01 

100.0 

Results 

(a)  Electrolytic  Iron.  A  sample  of  doubly  refined  electrolytic 
iron  serving  as  our  standard  of  low  carbon  iron  was  analyzed  ac- 
cording to  the  above  method,  giving  the  following  results: 


CARBON 


95 


Table  IV 


Carbon  Content  of  Electrolytically  Refined  Iron. 
Standard  Sample.     5  g.  Samples. 


g 

Sample    Heated    in 

Sample  Heated  to  and  at  1000°.     Tube  Filled 
with  O2  and  Evac. 

Net  Carbon  Obtained 

U 

Vacuo  to  600°* 

I 

8 

1st  Period 

2d  Period 

1st 

and 

Below 

At 

w 

2d 

600° 

1000° 

y, 

V 

Carbon  Obtained 

Carbon  Obtained 

Carbon  Obtained 

Car. 

Ad- 

Com- 

Total 

Is 

B 

Obt'd 

sorbed 

bined 

H 

1 

Gross 

Blank 

Net 

Gross 

Blk. 

Net 

Gross 

Blk. 

Net. 

Net. 

Min. 

Min. 

Mg. 

Mg. 

Mg. 

Min 

Mg. 

Mg. 

Mg. 

Min 

Mg. 

Mg. 

Mg. 

Mg. 

Percent 

Percent 

Percent 

110 

18 

20 

0.286 

0.019 

0.267 

31 

0.219 

0.031 

0.188 

29 

0.093 

0.037 

0.056 

0.244 

0.0053 

0.0049 

0.0102 

111 

15 

20 

0.320 

0.019 

0.301 

28 

0.220 

0.031 

0.199 

25 

0.067 

0.037 

0.030 

0,229 

0.0060 

0.0046 

0.0106 

112 

15 

20 

0.295 

0.019 

0.276 

28 

0.235 

0.031 

0.204 

29 

0.076 

0.037 

0.039 

0.243 

0.0055 

0.0049 

0.0104 

Mean  of 

Three 

Same 

IPS 

0.0056 

0.0048 

0.0104 

Variation  from  Mean  (±) 

0.0004 

0.0002 

0.0002 

*  Carbon  eliminated  during  2d  Period  at  600°  in  Vacuo  is  <  0.01  mg. 

These  results  show  that  the  total  carbon  content  of  this  material 
is  0.0104  (±0.0002)  percent.  The  important  fact  to  be  noted  from 
these  results  is  that  of  the  total  carbon  content,  more  than  half 
(0.0056  (±0.0004)  percent)  is  in  the  form  of  adsorbed  gases,  such  as 
CO  or  CO2,  given  off  at  or  below  600°,  and  that  the  combined  carbon 
content  is  only  0.0048  (±0.0002)  percent. 

The  above  standard  sample  of  electrolytic  iron  was  carefully 
analyzed  by  Mr.  C.  J.  Rottmann,  according  to  the  "Old"  method, 
the  average  of  11  separate  analyses  being  0.0177  percent  with  a  maxi- 
mum variation  from  the  mean  of  ±0.0080  percent.  This  amount 
includes  all  carbonaceous  matter  introduced  into  the  combustion 
tube,  i.  e.,  CO2  admitted  in  opening  and  closing  the  tube,  adsorbed 
gases  and  combined  carbon. 


In  order  to  determine  the  amount  of  CO2  admitted  to  the  combus- 
tion tube  while  removing  the  old  sample  and  introducing  the  new  one,  the 
gas  was  analyzed  during  the  preliminary  evacuation  with  the  sample 
cold.  Six  tests  gave  values  of  carbon  introduced  in  this  way  varying 
from  0.15  mg.  to  0.67  mg.  Based  on  a  5  g.  sample  this  corresponds 
to  0.0030 — 0.0134  percent.  The  results  are  tabulated  in  Table  V 
for  the  sake  of  comparing  the  "Old"  and  the  "New"  methods. 


96 


CARBON 


Table  V 

Comparison  of  "Old"  and  "New"  Methods  of  Analysis. 
Electrolytically  Refined  Iron.     Standard  Sample. 


"New"  Method 
Mean  of  3  Tests 
Percent  C 

"Old"  Method 
Mean  of  11  Tests 
Percent  C 

1. 

Carbon  introduced  while  opening  and 
closing  combustion  tube                 .... 

0.0080d=0  0050 

2 

Carbon  as  adsorbed  Gases  

0.0056  ±0.0004 

3 

Carbon  in  Combined  Form  

0.0048  ±0.0002 

Total, 

0.0184±0.0056 

0.0177  ±0.0080 

The  results  are  in  remarkably  close  agreement,  both  as  to  total 
carbon  and  as  to  variation.  It  will  be  noted  that  the  variation  is 
largely  due  to  item  1,  namely  carbonaceous  gases  introduced  into  the 
combustion  tube  while  opening  and  closing  the  tube,  gases  that  have 
no  connection  with  the  sample  at  all,  but  amounting  to  30-130  percent 
of  the  total  carbon  content  (items  2  and  3).  This  fact  explains  the 
large  variation  usually  obtained  in  the  carbon  content  of  low-carbon 
iron. 

(&)  Vacuum  Fused  Electrolytic  Iron.  Table  VI  shows  some  re- 
sults obtained  with  electrolitic  iron  after  being  melted  in  a  vacuum 
furnace  and  forged  into  rods.  2-202  and  2-210  were  melted  in  an 
Arsem  type  furnace  and  2-251  in  a  Tungsten  wound  furnace. 

(C)  Bureau  of  Standards  Samples.  As  a  check  of  the  constants 
of  the  apparatus  two  of  the  Bureau  of  Standards  standard  steel 
samples  were  analyzed,  the  results  being  given  in  Table  VII. 

Judging  from  these  results  the  agreement  is  as  close  as  can  be 
expected,  and  the  conclusion  is  justified  that  the  constants  of  the 
apparatus  are  correct'5. 


Modifications  of  the  Method. 

The  apparatus  as  described  in  this  paper  is  necessarily  elaborate, 
especially  the  analyzing  part  of  it,  in  order  to  eliminate  all  possible 
errors.  However,  great  simplifications  can  be  made  to  meet  the 
requirement  of  different  users.  In  another  apparatus  used  in  this 
laboratory  the  anlyzing  system  consists  of  two  good  stopcocks, 

5  It  should  be  noted  that  for  such  large  carbon  contents,  the  accuracy  of  the  apparatus  is  not  as 
great  as  for  smaller  carbon  contents,  because  in  the  former  case  the  pressures  are  too  large  to  be  read 
on  the  McLeod  gage  and  must  be  read  on  the  barometer  directly.  In  the  above  cases  the  pressures 
were  in  the  neighborhood  of  20  mm.,  and  the  readings  can  be  read  with  an  accuracy  of  only  ±  0.5 
mm.,  resulting  in  probable  errors  of  ±  2.5  percent. 


CARBON 


97 


Table  VI 
Vacuum  Fused  Electrolytic  Iron.     5  g.  Samples. 


Test 
No. 

121 
119 
120 

Sample 
No. 

Description  of  Sample 

Net  Carbon  Obtained 

600° 
Percent 

1000° 
Percent 

Total 
Percent 

2-202 
2-202 
2-202 

As  forged.      Outer  half  of  Rod,  except 
surface      Ether  cleaned      .            .    . 

0.0104 
0.0000 
0.0000 

0.0159 
0.0038 
0.0045 

0.0263 
0.0038 
0.0045 

Forged  and  Annealed  in  Vacuo.    All  of 
Rod  except  surface.     Not  cleaned  .  . 
Forged  and  Annealed  in  Vacuo.    All  of 
Rod  except  surface.    Ether  cleaned. 

115 

116 
114 
117 

2-210 
2-210 
2-210 
2-210 

As  forged.    Outer  half  of  Rod,  except 
surface.     Not  cleaned     

0.0027 
0.0015 
0.0004 
0.0009 

0.0042 
0.0039 
0.0030 
0.0015 

0.0069 
0.0054 
0.0034 
0.0024 

As  forged.    Outer  half  of  Rod,  except 
surface.     Ether  cleaned  
As  forged.       Center  of  Rod.       Ether 
cleaned 

Forged  and  Annealed  in  Vacuo.   All  of 
Rod  except  surface.     Not  cleaned  .  . 

122 

2-251 

As  forged.       Center  of  Rod.       Ether 
cleaned  

0.0006 

0.0025 

0.0031 

Previous  analyses  by  the  "Old"  method  have  given  0.02-0.04    percent  [Carbon  for  the  above 
samples,  *.  e.,  up  to  10  times  what  the  "New"  method  gives. 

a  liquid  air  trap,  and  a  long  mercury  column  similar  to  the  arrange- 
ment shown  on  Page  88,  and  it  gives  very  satisfactory  results.  Further- 
more, split  furnaces  can  be  used,  arranged  on  swinging  arms,  thus 
doing  away  with  the  long  combustion  tube.  This  modification 
would  probably  result  in  lower  blanks,  because  the  carbon  obtained 
in  the  blanks  is  probably,  in  part  at  least,  due  to  diffusion  of  CO2  from 
the  atmosphere  through  the  heated  portions  of  the  tube.  Finally 
the  mercury  diffusion  pump  may  be  eliminated,  depending  entirely 
on  the  oil  pump  for  evacuation.  This  is  done  in  the  apparatus  re- 
ferred to  above.  In  short,  the  apparatus  can  be  made  as  simple  or 
as  elaborate  as  the  requirements  call  for. 

Summary  and  Conclusions. 

1.  It  has  been  shown  in  this  paper  that  by  the  method  described 
great  accuracy  in  determining  the  products  of  the  combustion  tube 
is  possible ;  0.001  mg.  carbon  can  readily  be  measured  by  the  analyzing 
system. 

2.  The  blanks  of  the  apparatus  are  small  and  consistent,  the 
maximum  variations  amounting  to  only  ± 0.007  mg.  carbon,  which 
is  the  probable  error  of  the  apparatus.       This,  for  a  10  g.  sample 


CARBON 


containing  0.01  percent  carbon  would  result  in  an  error  of  ±  0.00007 
percent  carbon  or  0.7  percent  of  the  total.  This  is  100  times  better 
than  is  possible  by  any  of  the  present  methods. 

Table  VII 

Analysis  of  Bureau  of  Standards  Standard  Samples. 
2  g.  Samples. 


No.  20a  Acid  Open  Hearth  Steel,  0.4  percent  Carbon. 

the  Bureau  of  Standards,  0.393  percent  Carbon. 
No.  15a  Basic  Open  Hearth  Steel,  0.1  percent  Carbon. 

the  Bureau  of  Standards,  0.109  percent  Carbon. 


Containing,  according  to 
Containing,  according  to 


Test 
No. 

Sample 

Net  Carbon  Obtained 

600° 
Percent 

1000° 
Percent 

Total 
Percent 

102 
103 

105 

106 
107 

No.  20a  .                    

0.015 
0.010 

0.367 
0.365 

0.381 
0.375 

No.  20a  

Mean 

0.0125 
0.0025 

0.366 
0.001 

0.378 
0.003 

Variation  from  Mean  (->-) 

No.  15a                                                          .... 

0.005 
0.009 
0.006 

0.112 
0.094 
0.101 

0.117 
0.103 
0.107 

No.  15a                                

No.  15a.                             

Mean  

0.007 
0.002 

0.102 
0.010 

0.109 
0.007 

Variation  from  Mean  (db)  

3.  By  carrying  out  the  analysis  in  three  stages,  namely  (a)  with 
the  sample  evacuated  cold,  (b)  heated  to  600°  in  vacuo,  and  (c)  heated 
to   1000°   in  oxygen,  it  is  shown  that  the  total  amount  of   carbon 
obtained   from   electrolytic   iron   is   divided   about   equally   between 
(a),  (b)  and  (c) ;    in  other  words,  that  about  0.005  percent  is  due  to 
gases  admitted  to  the  tube  in  introducing  the  sample,  that  about 
0.005  percent  is  present  in  the  iron  as  adsorbed  or  occluded  gas,  and 
that  the  remainder  0.005  percent  is  the  combined  carbon. 

4.  A  great  deal  of  variation  exists  in  the  amount  of  carbon 
obtained  during  the  first  stage  of  analysis,  (3a),  and  it  has  been  shown 
that  the  great  variations  in  the  carbon  contents  of  low  carbon  iron 
usually  obtained  may  be  attributed  to  this  source. 

5.  The  new  method  can  be  modified  to  suit  any  given  condition; 
but  for  carbon  contents  of  0.10  and  above  the  established  methods, 
when  carefully  carried  out,  are  sufficiently  reliable  to  make  more  re- 
fined methods  unnecessary.       It  is  only  for  very  low  carbon  contents 


CARBON 


that  the  errors  in  the  established  methods  are  so  large  as  to  conceal  the 
true  condition. 

The  author  wishes  to  express  his  appreciation  to  Mr.  A.  L.  Shields 
for  his  conscientious  work  in  connection  with  the  analyses  and  to  Mr. 
C.  J.  Rottmann  for  his  valuable  advice  based  on  his  large  experience 
in  all  matters  pertaining  to  analytical  chemistry. 

Westinghouse  Research  laboratory, 
January  15,  1920. 


100:     : 


CARBON 


Drilling  pig  iron  for  chemical  analysis.       All  pig  iron  is  carefully  analyzed,  five 
samples  being  taken  from  each  car-load  received 


CARBON 


CARBON 

AN  ELECTROLYTIC  RESISTANCE  METHOD  FOR 
DETERMINING  CARBON  IN  STEEL1 

By  J.  R.  Cain  and  I.  C.  Maxwell2 
INTRODUCTION 

The  purpose  of  this  study  was  to  investigate  the  accuracy,  speed, 
practicability  of  a  method  for  determining  carbon  in  steel,  dependent 
in  principle  on  passing  the  carbon  dioxide  produced  by  direct  com- 
bustion of  the  metal  into  a  solution  of  barium  hydroxide  of  known 
electrical  resistance;  after  complete  absorption  of  this  gas  the  re- 
sistance is  again  determined  and  from  the  increase  in  this  (due  to 
precipitation  of  barium  ions)  the  percentage  of  carbon  is  deduced. 
This  method  is  new  in  principle  and  it  is  believed  that  the  principle 
can  be  applied  generally  in  many  cases  where  the  substance  being 
determined  precipitates  another  substance  from  solution  with  re- 
sultant change  in  resistance.  The  assembly  of  apparatus  for  de- 
termining resistance  is  also  new,3  and  offers  many  advantages  for 
technical  work  over  the  methods  hitherto  in  general  use  for  measure- 
ment of  electrolytic  resistances,  which  require  the  use  of  induction 
coils  or  high  frequency  generators,  tuned  telephones,  balanced  in- 
ductances and  capacities,  etc.  Other  new  features  are  the  application 
of  the  nomograph4  for  the  graphical  representation  of  resistance  data 
and  the  use  of  special  conductivity  cells  with  adjustable  electrodes  to 
facilitate  the  manufacture  of  any  number  of  such  cells  with  the  same 
cell  constant. 

Much  work  has  been  done  by  others  on  electro-chemical  analytical 
methods.  In  general,  these  fall  into  three  groups  in  which  an  end- 

1  Complete  equipment  for  determination  of  carbon  by  this  method  may  be  obtained  from  Arthur 
H.  Thomas  Co.,   Philadelphia. 

2  Journal  of  Industrial  and  Engineering  Chemistry,  Vol.  11,  No.  9,  page  852.  September,  1919. 

3  The  elements  of  this  were  described  by  Weibel  and  Thuras,  This  Journal,  10  (1918),  626. 

4  The  mathematical  work  in  constructing  the  nomograph  shown  on  page  112  was  done  by  Mr.  H. 
M.  Roeser  of  the  Bureau  of  Standards  at  the  request  of  the  senior  author,  who  suggested  its  appli- 
cation to  electrolytic  resistance  data.       A  paper  on  this  subject  is  in  preparation  by  Mr.  Roeser. 
References  on  the  nomograph  are:       "Traite  de  Nomographie,"  by  M.  d'Ocagne,  Gauthiers-Villars, 
Paris;  "Graphical  Methods,"   by   Carl   Runge,    Columbia   University   Press,   New  York;   "Graphical 
Interpolation   of  Tabulated  Data,"  by  H.  G.  Deming,  J.  Am.  Chem.  Soc.,  39  (1917),    2388;  "The 
Nomon,  a  Calculating  Device  for  Chemists,"  by  H.  G.  Deming,  Ibid.,  39  (1917),  2137. 


\18fc.%r  :'/:*?;  S3      S  /.   '   ";  CARBON 

point  is  shown  electrochemically  by  the  following  methods:  (1)  The 
unknown  concentration  is  obtained  from  curves  expressing  a  relation 
between  cubic  centimeters  of  titrating  solution  and  conductivity 
(or  a  related  quantity)  of  the  solution  titrated  j1  (2)  the  unknown  is 
obtained  from  curves  giving  the  relation  between  cubic  centimeters 
of  titrating  solution  added  and  the  corresponding  electromotive  forces 
of  a  cell  composed  of  a  normal  electrode  and  an  electrode  not  acted 
upon  by  the  solution  being  titrated,  the  latter  being  the  electrolyte;2 
(3)  special  application  of  Method  2  used  for  determining  hydrogen  ion 
in  acidimetry  sjrfd  alkalimetry  and  in  precipitations  from  neutralized 
solutions.3 


Such  methods  suffer  by  comparison  with  the  present  for  the 
following  reasons:  (1)  A  curve  has  to  be  plotted  for  every  determina- 
tion, which  consumes  much  time;  (2)  the  apparatus  required  to  de- 
termine carbon  with  an  accuracy  of  0.01  per  cent  carbon  would  be  too 
delicate  and  inconvenient  of  manipulation  for  every-day  use;  (3) 
the  difficulty  in  some  cases  of  fixing  with  sufficient  definiteness  the 
inflection  or  break  in  the  curve  denoting  the  end-point  of  the  titration. 
Upon  further  comparing  these  methods  with  the  present,  it  is  seen 
that  the  latter  dispenses  with  one  operation  common  to  all  the  others, 
namely,  the  addition  of  successive  portions  of  a  titrating  solution  and 
the  determination  of  the  resistance  at  each  addition,  resulting  in  ad- 
ditional time-saving. 

From  an  inspection  of  the  chemical  equation  for  the  reaction 
underlying  the  present  method, 

Ba(OH)2  +  CO2  =  BaCO3  +  H2O, 

it  is  evident  (when  any  given  conductivity  cell  is  used)  that  the  only 
factors  which  act  to  change  the  conductivity  of  the  barium  hydroxide 
used  for  absorption  are  (1)  the  amount  of  carbon  dioxide  absorbed, 
which  determines  the  disappearance  from  solution  of  the  barium  ion, 
and  (2)  the  temperature.  Since  carbon  dioxide  precipitates  barium 
without  leaving  reaction  products  in  the  solution  to  increase  the  con- 
ductivity (such  as  would  remain  if,  for  instance,  sodium  sulfate  were 
the  precipitating  agent  for  the  barium)  it  can  be  seen  that  the  present 

1  Harned,  J.  Am.  Chem.  Soc.,  39  (1916),  252;  Findlay,  "Practical  Physical  Chemistry,"  Ostwald- 
Luther,  "Physikalisch-Chemische  Messungen." 

2  Loomis  and  Acree,  Am.  Chem.  J.,  46  (1911),  585,  621  (a  bibliography  is  also  given);  Hildebrand, 
J.  Am.,  Chem.  Soc.,  35  (1913),  869;  Kelly,  Ibid.,  38  (1916.)  341. 

3  Hildebrand,  Loc.  cit.       See  also  Weibel  and    Thuras,    Journal    of  Industrial    and    Engineering 
Chemistry,  10  (1918),  626,  for  another  electrolytic  method. 


CARBON  103 

method  should  give  the  maximum  possible  change  of  resistance  for  a 
given  amount  of  barium  removed — a  condition  tending  to  secure  a 
high  degree  of  sensitiveness.1  However,  the  temperature  coefficients 
of  resistance  of  barium  hydroxide  solutions  in  the  range  of  concentra- 
tions herein  employed  average  nearly  1.7  per  cent  per  degree, 
hence  it  is  evident  that  the  accuracy  of  the  method  will  be  largely 
affected  by  temperature  if  due  correction  is  not  made. 

In  developing  this  method  it  was  deemed  necessary:  (1)  To  con- 
struct the  curve  showing  resistance  as  a  function  of  concentration  of 
barium  hydroxide  solutions  ranging  from  very  concentrated  to  very 
dilute  and  to  select  the  portion  of  this  curve  showing  the  maximum 
change  of  resistance  for  a  given  change  of  concentration ;  (2)  to  devise 
an  apparatus  which,  when  the  selected  barium  hydroxide  solutions 
were  used  in  it,  would  completely  absorb  the  carbon  dioxide  at  the 
highest  rates  of  passage  of  the  gas  current.  The  same  absorption 
apparatus,  in  order  that  the  method  might  meet  the  requirements  of 
convenience  and  rapidity,  should  permit  resistance  determinations 
to  be  made  without  transfer  of  the  solution  to  another  vessel;  it 
should  also  be  easy  to  fill  and  empty ;  (3)  to  determine  the  temperature 
coefficients  of  the  barium  hydroxide  solutions  in  the  selected  range  of 
concentration;2  (4)  to  prepare  a  chart  enabling  the  operator  to  read 
directly  therefrom  the  percentage  of  carbon,  all  temperature  cor- 
rections being  incorporated ;  (5)  to  design  an  apparatus  for  the  elec- 
trical measurements  possessing  the  necessary  robustness,  reliability, 
simplicity,  and  protection  from  corrosion  by  the  laboratory  fumes. 

The  Resistance  of  Barium  Hydroxide  Solutions 

A  curve  was  prepared  showing  the  relation  between  electrical 
resistance  and  barium  hydroxide  concentration  when  the  latter  was 
varied  from  practically  saturation  to  nearly  zero.  The  data 
in  the  literature  being  insufficient  for  this  purpose,  the  de- 
terminations were  made  by  Mr.  Louis  Jordan  of  this  Bureau  and 
are  represented  on  Page  104.  The  solutions  for  constructing  the  curve 
were  prepared  from  J.  T.  Baker's  analyzed  barium  hydroxide 
by  diluting  a  stock  solution  of  this  with  carbon  dioxide-free  water  and 
determining  their  strength  by  titration  against  standard  hydrochloric 
acid  using  methyl  orange  as  indicator.  The  resistance  measurements 
were  all  made  in  the  same  conductivity  cell  and  at  practically  the  same 

1  Compare  the  conditions  in  Harned's  work  with  Ba(OH)2  solutions.     Loc.  cit. 

2  There  is  some  possibility  of  placing  the  absorption  vessel  in  a  constant  temperature  bath  to- 
gether with  a  compensating  cell  in  the  other  arm  of  the  bridge.       This  would  remove  the  necessity 
for  temperature  correction.       The  method  described  herein,  however,  is  believed  to  be  simpler. 


104 


CARBON 


temperature   (27°    C.)1.        No   great  accuracy   is  claimed   for    these 
results,  which  are  used  only  for  establishing  the  form  of  the  curve  and 


60. 
50. 
40. 
30. 
20. 
10 


•     ,    .     ,,     ,        :  ." 

l%2%3%4*5%  10% 


G«AMS  BA(OH)2  PERIOD  cc. 

V       s.0        6.0        r.o        3,0       ao 
15%  2i>%          ds%          3fe%* 

%CAR30N 


selecting  a  portion  of  it  for  more  exact  redetermination.  The  portion 
of  the  curve  selected  for  use  in  this  method  is  that  between  A  and  B. 
This  region  gives  the  maximum  change  of  resistance  per  unit  change  of 
concentration  consistent  with  the  use  of  solutions  sufficiently  con- 
centrated to  effect  complete  absorptions  of  carbon  dioxide  under  the 
conditions  imposed.  Comparing  the  resistance  changes  with  changes 
of  concentration  of  barium  hydroxide  corresponding  to  1  per  cent 
carbon  on  different  parts  of  the  curve,  it  is  seen,  for  example,  that  these 
changes  in  resistance  are  approximately  six  times  as  great  on  the  portion 

1  They  were  not  corrected  by  any  temperature  coefficient  since,  as  an  inspection  of  Table  1  shows, 
they  were  made  at  near  enough  to  one  temperature  to  give  roughly  the  form  of  the  curve,  which  was 
all  that  was  desired. 


CARBON 


105 


AB  as  on  the  portion  CD.  The  use  of  the  most  dilute  solutions 
possible  is,  of  course,  also  desirable  from  the  saving  in  barium  hydroxide 
effected.  Solutions  to  the  left  of  A,  even  when  used  in  very  efficient 
absorbing  vessels  will  not  retain  all  the  carbon  dioxide  except  at 
rather  slow  rates  of  aspiration. 


TABLE  I — Data  for  Resistance-ConcentrationCurve  for    Ba(OH)  Solutions  in   the 
Region  2  Per  Cent  to  30  Per  Cent  Carbon  Equivalent  Strength 

Cell  Constant  =  0.715 
Ba(OH)2 

per  200  cc.  Soln.  Equivalent  t  Temperature  Resistance 

Grams  Per  cent  Carbon  Deg  C.  Ohms 


0.612 

1.12 

1.68 

2.20 

2.67 

3.17 

3.64 

4.05 

4.43 

4.94 

5.31 

5.88 

6.45 

6.93 

7.34 

7.84 

8.45 


2.14 
3.92 
5.87 
7.70 
9.35 
11.1 
12.7 
14.2 
13.5 
17.9 
18.6 
20.6 
22.5 
24.2 
25.6 
27.4 
29.5 


27.9 
27.3 
27.3 
27.3 
27.3 
27.2 
27.0 
26.9 
27.0 
27.2 
27.0 
26.9 
26.0 
26.8 
21.2 
21.2 
27.3 


171.6 
97.9 
68.5 
53.5 
44.9 
38.7 
34.6 
31.2 
29.2 
26.2 
24.7 
22.7 
21.8 
20.1 
20.8 
19.7 
16.4 


1  The  method  used  in  Tables  I  and  II  and  elsewhere  throughout  this  paper  for  expressing  the 
strength  of  the  barium  solution  in  terms  of  "equivalent  per  cent  carbon"  was  chosen  for  convenience 
in  using  the  nomograph  described  subsequently.  By  "equivalent  per  cent  of  carbon"  is  meant  the 
amount  of  carbon  expressed  as  percentage  on  the  basis  of  2-g.  samples  being  used,  necessary  to  pre- 
cipitate completely  all  the  barium  ions  from  the  solution  concerned.  This  amount  of  carbon  is 
calculated  from  the  equation;  Ba(OH)2  +  CO2  =  BaCO3  -f-  H2O.  For  instance,  in  the  first 
horizontal  column  of  this  table  it  is  seen  that  2.14  "equivalent  per  cent  carbon"  corresponds  to  0.612 
g.  Ba(OH)2;  the  former  figure  was  obtained  by  solution  of  the  proportion: 


Mol.  Wt.  Ba(OH)2  :  At.  Wt.  Carbon  ::  Wt.  of  Ba(OH)2  in  200  cc. 
Sample 

171.38  :  12.00  ::  0^612  :  X 

whence  X  —  0.0428  g.  carbon 

or  the  "equivalent  per  cent  carbon"  =  (*/2)100  —  2.14. 


Soln.   :  Wt.  of   Carbon   in 


The  portion  of  the  curve  selected  for  use  by  this  method  is  again 
shown  on  Page  107.  The  procedure  used  in  determining  the  points  on  it 
was  the  same  as  for  constructing  the  curve  shown  on  Page  104,  except 
that  more  care  was  taken  to  secure  accurate  readings  and  the  resultswere 
corrected  by  the  coefficients  given  under  the  heading  "Temperature 
Coefficients."  Table  II  gives  the  data  used  in  constructing  this 
curve. 


106  CARBON 

TABLE  II — Data  for  Resistance-Concentration  Curve  of  Ba(OH)8  Solutions  in  the 
Region  4  Per  cent  to  5  Per  cent  Carbon  Equivalent  Strength 

Cell  Constant  =  0.715 

Ba(OH)2  per  Observed  Corrected 

200  cc.  Soln.         Equivalent  Temperature  Resistance  Resistance 

Grams  Per  cent  Carbon  Deg.  C.  Ohms  Ohms 

1.164  4.075  23.6  100.9  98.49 

.198  4.194  24.2  97.4  96.08 

.239  4.337  24.2  94.6  93.26 

.242  4.348  23.2  95.8  92.81 

.280  4.482  24.4  91.4  90.42 

.286  4.500  26.6  87.6  90.01 

1.301  4.553                .        27.5  85.3  88.92 

1.303  4.559  26.4  86.8  88.79 

1.346  4.712  25.1  86.0  86.06 

1.385  4.848  25.8  82.7  83.90 

1.403  4.912  24.4  84.2  83.94 

1.460  5.110  23.1  82.8  80.11 

The  Absorption  Apparatus 

The  essential  features  desirable  in  the  absorption  apparatus  are: 
(1)  It  must  retain  all  carbon  dioxide  when  gas  passes  at  the  rate  of 
300  to  400  cc.  per  min.;  (2)  it  must  permit  resistance  measurements 
"to  be  made  without  transfer  of  the  solution  to  another  cell;  (3)  tem- 
peratures of  solutions  should  be  easily  read  to  0.1°  ;  (4)  the  cell  should 
be  easy  to  clean  and  fill  with  fresh  solution ;  (5)  all  cells  should  be  built 
with  the  same  cell  constant,1  or  the  latter  should  be  capable  of  ad- 
justment to  one  value  for  all,  so  that  the  chart  or  set  of  tables  may  be 
used  for  all  cells. 

Fleming2  and  others  have  shown  that  the  combustion  of  a 
sample  of  steel  and  the  sweeping  out  of  the  products  of  combustion 
from  the  apparatus  where  combustion  tubes  of  the  usual  length  and 
bore  are  used,  can  be  accomplished  in  5  to  6  min. ;  this  requires  passage 
of  the  oxygen  at  the  rate  of  about  300  to  400  cc.  per  min.  Soda  lime 
has  been  found  to  absorb  all  the  carbon  dioxide  at  this  and  higher  rates. 
However,  barium  hydroxide  solutions  of  all  concentrations  are  much 
less  efficient  absorbents  than  soda  lime.  The  absorbing  efficiency 
increases  slightly  with  the  concentration,  but  even  when  the  most 
concentrated  solutions  were  used  it  was  impossible  to  absorb  com- 
pletely all  the  carbon  dioxide  in  the  usual  types  of  gas  absorption 
vessels,  nearly  all  of  which  were  tried.  The  method  of  testing  these 
forms  of  apparatus  was  to  burn  a  sample  of  steel,  having  a  gas  meter 
before  the  furnace  to  control  the  rate  of  passage  of  the  oxygen,  and  to 

1  The  "cell  constant"  is  not  a  constant  at  all,  as  Washbourne  and  others  have  shown,  but  for  want 
of  a  better  term  this  expression  has  been  used  throughout  this  paper. 

2  Iron  Age,  93  (1913),  64. 


CARBON  107 

attach  after  the  tube  being  tested  a  second  absorption  vessel  con- 
taining a  little  clear  barium  hydroxide  solution;  a  test  was  not  con- 
sidered satisfactory  if  the  second  tube  showed  any  cloudiness. 

Satisfactory  absorption  was  secured  in  a  vessel  similar  to  that 
described  by  Weaver  and  Edwards,1  with  suitable  modifications,  the 
details  of  which  were  developed  by  Mr.  S.  M.  Hull,  formerly  of  the 
Chemical  Division  of  the  Bureau  of  Standards.  For  use  in  the 
present  work,  electrodes  were  sealed  into  this  absorption  tube  in  the 
middle  reservoir.  In  order  always  to  secure  the  same  cell  constant, 
the  area  and  distance  apart  of  the  electrodes  were  originally  adjusted 
before  sealing  into  the  reservoir.  This  was  found  to  be  an  extremely  un- 
certain and  difficult  operation,  and  this  difficulty  as  well  as  the  general 


fragility  of  the  apparatusled  to  its  abandonment  and  the  search  for  some- 
thing simpler.  After  the  completion  of  investigationsdescribedin  another 
paper,2  it  was  found  that  by  burning  the  sample  as  therein  described 
(namely,  by  placing  it  on  a  preheated  boat,  allowing  boat  and  sample 
to  further  preheat  for  a  minute  in  the  furnace  and  then  admitting 
oxygen  at  300  to  400  cc.  per  min.),  it  was  possible  to  completely  burn 
a  2-g.  sample  in  1^  to  2  min.  Since  the  first  few  hundred  cubic 
centimeters  of  oxygen  combine  with  the  iron,  there  is  produced  a 

1  Journal  of  Industrial  and  Engineering  Chemistry,  7  (1915),  534. 

2  Cain  and  Maxwell,  Journal  of  Industrial  and  Engineering  Chemistry,  10  (1918),  520. 


108 


CARBON 


CARBON  109 

much  better  partial  pressure  of  carbon  dioxide  than  is  secured  where  a 
sample  burns  slowly  and  this  makes  it  possible  to  use  a  very  simple 
absorption  tube,  such  as  that  shown  on  Page  108,  for  the  carbon  dioxide. 

It  was  also  found  simpler  to  build  a  cell  whose  electrodes  could  be 
adjusted  to  secure  a  given  cell  constant  than  to  attempt  to  obtain  the 
same  result  with  the  electrodes  sealed  in  a  fixed  position  in  the  cell. 
This  fact  and  the  use  of  the  special  method  of  combustion  described 
led  to  the  design  of  the  apparatus  shown  on  Page  108.  This  is  not  fragile 
and  the  glass  parts  can  be  built  by  any  glass  blower  of  ordinary  skill ; 
it  meets  all  the  listed  requirements  of  the  absorption  apparatus. 

The  adjustment  of  the  cell  constant  is  made  by  moving  the 
electrodes  up  and  down  after  loosening  the  stuffing  box;  a  marked 
change  takes  place  as  they  approach  the  meniscus.  Initial  approxi- 
mate similarity  can  be  attained  by  the  glass  blower  with  comparative 
ease.  Once  the  electrodes  are  set  in  the  proper  position,  this  is  main- 
tained by  cementing  with  DeKhotinsky  cement.  The  electrodes  are 
platinized  and  the  cell  constant  is  determined  as  described  under  "Oper- 
ating Suggestions."  A  certain  amount  of  adjustment  of  the  constant 
of  the  cell  can  be  secured  by  removing  or  adding  platinum  black  to  one 
or  the  other  of  the  electrodes  during  the  platinizing  operation  by  the 
use  of  an  auxiliary  electrode.  Some  cells  in  long  use  at  the  Bureau 
have  differed  in  cell  constant  by  0.04  without  affecting  the  accuracy 
of  results.  Actually,  it  is  easily  possible  to  adjust  cell  constants 
within  0.005,  and  this  practice  is  to  be  recommended. 

Temperature  Coefficients 

The  solutions  for  determination  of  these  coefficients  were  prepared 
and  standardized  as  already  described.  The  conductivity  cells  used 
for  the  work  were  kept  in  a  thermostatically  controlled  chamber  where 
the  temperatures  were  maintained  within  0.01°  C. 

Resistances  of  barium  hydroxide  solutions  equivalent  to  ap- 
proximately 4.0,  4.25, 4. 50, 4. 75,  and  5.0  per  cent  carbon  were  determined 
at  20°,  25°,  and  30°.  The  experimental  values  and  the  corresponding 
calculated  values  for  a  and  B  are  shown  in  Table  III.  These  values 
for  a  and  B  were  calculated  by  substituting  the  values  for  temperature 
and  resistance  from  Table  III  for  t  in  the  equation 
1  1  +  a[t— 25]  +  B[t— 25]2, 


Rt  R25 

and  solving  for  a  and  B. 


110  CARBON 

Methods  for  Direct  Reading  of  Carbon  Percentages 

Several  methods  were  tried  for  graphically  representing  the  rela- 
tion between  carbon  percentages  and  the  corresponding  observed 
temperature  and  resistance  measurements.  At  first  tables  were 
constructed  in  which  temperature  corrections  were  calculated  and 
applied  for  every  tenth  of  a  degree  and  every  tenth  of  an  ohm,  but 
these  were  found  to  be  too  cumbersome.  •  Other  tables  were  then 
constructed  giving  the  temperature  corrections  only,  with  the  idea  of 
adding  or  subtracting  these  each  time  a  reading  was  made.  This 
condensed  the  tables  very  considerably  but  increased  the  amount  of 
calculation  necessary.  A  series  of  curves  was  then  constructed 
showing  the  relation  between  resistance  and  per  cent  carbon,  a  curve 
being  constructed  for  every  tenth  of  a  degree.  Such  curves  are  con- 
venient to  use  only  if  they  are  plotted  on  an  inconveniently  large  scale ; 
even  then  it  is  very  fatiguing  to  use  them  for  many  readings  at  a  time. 

TABLE   III — Data  for  Temperature  Coefficients  of  Resistance 

Concn.    of 
Ba(OH)2  Soln.1 

Per  cent  C.         Temperature         Resistance 

Approx.                 Deg.  C.  Ohms                           a                        B  X  10-4 

5.0                          20  135.25                    0.01674                      0.2687 

25  124.02 

30  114.37 

4.75                        20  142.18 

25  130.36                    0.01680                      0.3505 

30  120.16 

4.50                        20  149.07 

25  136.62                    0.01686                      0.3085 

30  125.91 

4.25                        20  156.18 

25  143.07                    0.01687                      0.1652 

30  131 .89 

4.00                        20  165.18 

25  151.28                    0.01687                      0.0898 

30  139.48 

1 — 200  cc.  of  the  solution  contained  barium  hydroxide  approximately  equivalent  to  the  carbon 
in  a  2-g.  sample  with  5  per  cent  C,  or  100  cc.  of  the  solution  contained  barium  hydroxide  approximately 
equivalent  to  the  carbon  in  a  1-g.  sample  with  5  per  cent  C;  or  approximately  0.7125  g.  Ba(OH).,. 
The  other  solutions  contained  barium  hydroxide  approximately  equivalent  to  1-g.  samples  with  4.75 
per  cent,  4.50  per  cent,  and  4.25  per  cent,  4.00  per  cent,  respectively. 

After  a  little  study  it  was  found  that  the  B  term  could  be  omitted 
from  the  equation  for  correcting  temperatures  to  25°,  provided  this 
equation  is  applied  only  between  the  temperatures  15°  and  35°  ;  at 
higher  or  lower  temperatures  the  correction  for  the  B  term  is  ap- 
preciable. If  the  laboratory  temperature  is  not  within  these  limits, 


CARBON  111 

the  stock  solution  in  carboy  F  on  Page  114  must  be  brought  within  this 
range  by  placing  it  in  a  bath  of  cold  water.  The  equation 

(1)  R25  =  R/[l  +  a(t  —  25)  +  B(t—  25)2 

-  then  reduces  to 
R/ 

R25  =  R/[l  +  a(t  —  25)],  in  which  a  =  0.01681,  this  value  being 
taken  from  Table  III.  After  trials  of  other  forms  of  curves,  it  was 
found  that  the  parabolic  form  answered  the  requirements  of  fitting 
the  observations  sufficiently  well  and  of  permitting  the  construction 
of  a  nomograph;  the  equation  to  the  curve  shown  on  Page  107  was 
calculated  on  the  assumption  that  it  was  parabolic,  using  the  methods 
of  least  squares  and  the  observations  shown  in  Table  II.  This 
equation  was  found  to  be 

C2  —  13.589  C  +.  63.191  —  0.2478  R25  =  0 
or, 

C2  -  -  13.589  C  +  63.191  --  0.2478  [l  +  a(t  —  25)]  =  0  whence, 
(2)  C  =  6.79— }Wo.9912R(0.5798+.01681/— 67.11),  C  being  the 
equivalent  per  cent  of  carbon  in  the  sense  already  explained.  From 
Equation  2  the  nomograph  shown  on  Page  112  was  prepared.  This 
nomograph  can  be  used  for  all  cells  having  cell  constants  not  too  dif- 
ferent from  0.715,  which  was  the  cell  constant  of  the  cell  used  when 
data  for  the  curve  shown  on  Page  107  were  obtained.  As  has  been  shown, 
the  form  of  cell  used  allows  the  electrodes  to  be  adjusted  always 
to  secure  this  result.  (Page  108.) 

The  use  of  the  nomograph  is  very  simple.  A  straight  edge  is 
made  to  correct  the  observed  values  for  temperature  and  resistance 
and  the  intersection  with  the  third  (middle)  ordinate  gives  the  'con- 
centration of  the  solution  in  terms  of  carbon  percentage;  this  may  be 
termed  the  first  concentration.  After  the  combustion  is  ended  a 
similar  set  of  readings  is  taken  and  subtraction  of  the  second  con- 
centration reading  from  the  first  gives  directly  the  per  cent  of  carbon 
if  a  2-g.  sample  has  been  taken;  or,  if  a  1-g.  sample  has  been  used, 
the  result  is  multiplied  by  two.  The  scales  can  be  read  to  0.005  per 
cent  C,  0.05°  C.,  and  0.05  ohm.  It  was  found  by  comparison  of 
chart  readings  in  a  number  of  cases  with  the  resistances  computed  by 
Equation  1  that  the  error  of  the  chart  is  less  than  0.005  per  cent 
carbon. 


112 


CARBON 


.98 


4  ^-J3 


4.00 
+  10 
+ZO 


+  60 
470 


4-90 
SOO 


ti\ 

¥^*a 

fer*7 


78 
77 


--20 


CARBON 


113 


Apparatus  for  Determining  Electrical  Resistance 

With  the  co-operation  of  the  Leeds  and  Northrup  Company, 
different  forms  of  apparatus  for  measuring  electrolytic  resistances 
were  built  and  tried.  Two  forms  of  high  frequency  generator  in 
connection  with  tuned  telephones  were  used ;  also  one  or  two  forms  of 
induction  coil  as  sources  of  alternating  current,  and  an  interrupter 
such  as  is  used  in  wireless  investigations;  the  latter  was  quite  un- 
satisfactory, as  might  be  expected,  due  to  polarization.  Good  results 
were  obtained  with  the  high  frequency  generators  and  tuned  tele- 
phones, provided  that  inductances  and  capacities  were  used  as  directed 
by  recent  investigators.  Such  refinements  are  inconvenient  in  a 
method  such  as  the  present,  intended  for  works  use,  and  there  are  two 
other  important  objections  from  the  same  standpoint:  (1)  the  diffi- 
culty of  detecting  a  minimum  in  the  telephone  when  working  in  a 
noisy  place  such  as  the  usual  works  laboratory  and  the  fatigue  of  the 
operator  who  would  have  to  make  possibly  80  or  90  determinations 
in  an  8-hr,  day,  and  (2)  the  liability  to  deterioration  of  a  high  frequency 
generator  when  operating  continuously  24  hrs.  per  day  as  might  happen 
in  technical  use.  These  considerations  led  to  the  development  of  a 
method  of  measuring  electrolytic  resistances  by  the  use  of  commercial 
60-  or  25-cycle  current.  It  was  found  after  trial  of  the  Weibel1 
galvanometer,  a  vibration  galvanometer  and  of  a  direct  current  galvan- 
ometer operating  off  a  crystal  rectifier  placed  in  the  secondary  of  a 
transformer  (the  cell  being  in  the  primary),  that  the  Weibel  galvan- 
ometer offered  a  very  satisfactory  zero  instrument  for  such  measure- 
ments of  electrolytic  resistance  as  had  to  be  made  in  this  work. 


DIAGRAM  OF  BRIDGE  USED  FOR  RESISTANCE  MEASUREMENTS 

The  bridge  shown  on  Page  113  was  accordingly  constructed  by  Leeds  and 
Northrup.  The  resistance  coils  and  galvanometer  are  enclosed  in  a 
hermetically  sealed  box  so  that  they  are  efficiently  protected  from  cor- 

1  E.  E.  Weibel,  Bureau  of  Standards,  Scientific  Paper,  297   (1917). 


114 


CARBON 


JN-J 


rosion.  There  are  three  dials — tens,  units,  and  tenth  ohms,  respec- 
tively— and  a  fourth  which  adds  100  to  the  readings  of  the  others, 
when  this  is  desired.  An  accuracy  of  0.1  ohm  in  the  readings  is  all 
that  is  necessary,  although  much  better  than  this  can  be  done.  This 
instrument  has  been  in  use  several  months  and  has  been  very  satis- 
factory. A  perfect  minimum  is  always  registered  by  the  galvanome- 
ter, provided  the  electrodes  are  well  platinized. 


CARBON  115 

Procedure  for  Determining  Carbon 

A  nichrome-wound  furnace  is  used  for  heating.  Porcelain  or 
glazed  quartz  tubes  may  be  employed;  they  should  be  fitted  with  a 
sheet  nickel  sleeve  to  protect  internally  from  fused  iron  oxide  which 
is  thrown  off  from  the  burning  steel.  The  two  absorption  vessels  are 
rilled  to  the  200  cc.  mark  with  barium  hydroxide  solution  from  the 
stock  bottle  F  (Page  114;  see  also  Operating  Suggestion  1).  Oxygen 
or  air  freed  from  carbon  dioxide  is  passed  for  a  few  seconds  to  mix  the 
solutions  and  their  temperatures  and  resistances  are  then  recorded. 
In  the  meantime  the  combustion  boat  filled  with  alundum  sand  has 
been  preheating  in  the  furnace,  which  for  this  work  should  be  main- 
tained continuously  at  1050°  to  1100°,  perferably  the  latter  tempera- 
ture.1 This  is  an  extremely  important  point,  for  if  the  temperature 
is  too  low  or  the  oxygen  is  not  pure  or  is  not  admitted  at  300  to  400 
cc.  per  min.  after  the  combustion  starts,  the  rapid  combustion  es- 
sential to  successful  absorption  cannot  be  secured.  The  boat  is  re- 
moved from  the  furnace  and  when  at  a  low  red  heat  the  sample  is 
distributed  on  the  alundum2  and  the  boat  replaced  in  the  furnace  and 
left  to  preheat,  without  oxygen  passing,  while  the  next  sample  is  being 
weighed.  Oxygen  is  now  passed  at  the  rate  of  300  to  400  cc.  per  min. 
for  the  next  two  minutes;  then  the  stopcock,  is  turned  to  the 
position,  which  admits  carbon  dioxide-free  air;  this  should  pass  at  the 
same  rate  as  the  oxygen.  During  this  combustion  period,  if  directions 
have  been  followed,  all  carbon  dioxide  will  have  been  removed  from 
the  furnace,  but  some  still  remains  in  the  large  bulb  of  the  absorption 
apparatus.  The  air  removes  this.  The  advantage  of  the  use  of  air 
at  this  stage  is  obvious :  a  saving  of  oxygen  is  effected  and  the  furnace 
is  immediately  available  for  burning  the  next  sample.  While  air  is 
passing  through  the  first  tube  (requiring  \1A  to  2  min.)  the  combustion 
of  the  next  sample  proceeds  as  already  directed,  using  the  second 
absorption  tube.  The  second  reading  of  resistance  and  temperature 
on  the  first  tube  then  follows,  and  if  the  solution  is  not  too  dilute  it  can 
be  used  for  absorbing  the  carbon  dioxide  from  other  samples;  other- 
wise, a  little  is  allowed  to  flow  into  the  reservoir  G,  and  the  tube  is 
filled  to  the  mark  again  with  fresh  solution.  Of  course  it  is  an  economy 
in  time  for  the  operator,  wherever  possible,  to  choose  conditions 
(weight  of  sample,  carbon  content  of  same,  etc.)  so  as  to  get  the  maxi- 
mum number  of  determinations  for  a  single  filling,  since  in  this  way  the 

1  The  melting  point  of  gold  is  a  convenient  temperature  check.       If  this  metal  is  not  melted  the 
temperature  is  too  low.      See  paper  cited,  by  Cain  and  Maxwell. 

2  Experience  has  shown  that  no  loss  of  carbon  occurs  unless  the  sample  contains  extremely  fine 
particles;  with  most  steels  these  can  first  be  removed  without  causing  an  error  in  the  carbon  deter- 
mination.      This  point  should  always  be  tested,  however,  in  burning  new  steels. 


116 


CARBON 


second  resistance  and  temperature  readings  serve  as  initial  values  for 
the  next  combustion  and  so  on.  The  solution  should  not  be  used 
when  it  is  more  dilute  than  corresponds  to  4  per  cent  carbon  (i.  e.,  99.5 
ohms  at  25°  ;  see  nomograph,  on  Page  1 12,  for  the  limiting  resistances  cor- 
responding to  other  temperatures),  since  its  absorptive  power  at  rapid 
rates  of  passage  of  the  oxygen  is  then  less,  and  some  carbon  dioxide 
may  be  lost.  The  data  relating  to  combustions  should  be  recorded 
as  obtained.  It  is  convenient  to  use  a  tabular  form  for  record  showing : 
(1)  Designation  of  sample;  (2)  weight  taken;  (3)  cell  used;  (4)  initial 
temperature;  (5)  final  temperature;  (6)  initial  resistance;  (7)  final 
resistance;  (8)  initial  concentration;  (9)  final  concentration;  (10) 
carbon  percentage  in  sample;  (11)  remarks.  There  is  ample  time  for 
entering  this  information  while  other  operations  are  going  on.  A 
very  good  way  is  to  enter  "final  temperature"  below  "initial  tempera- 
ture," and  "final  resistance"  after  "initial  resistance"  for  each  sample, 
since  this  relates  these  quantities  in  an  easy  manner  for  reading  the 
nomograph. 

The  speed  of  the  method  naturally  depends  on  the  skill  of  the 
operator  and  the  ingenuity  displayed  in  arranging  a  cycle  of  operations 
which  secures  the  best  speed  under  his  working  conditions.  Operators 
at  the  Bureau  of  Standards  when  working  on  a  series  of  Bureau 
of  Standards'  analyzed  samples  averaged  one  determination  per  4J^  to 
5  min.  The  accuracy  of  results  is  shown  in  Table  IV. 

TABLE    IV — Results    by    Electrolytic    Resistance    Method 


B.  S. 
Standard 
Sample             1 
Used 

lla.  . 

B.  S.  Value  for 
Carbon  (Av. 
by  Direct 
A^t.  Used                   Combustion) 
Grams                            Per  cent 

2.0                                 0  223 

Value  by 
Electrolytic 
Resistance 
Method 

0.21 

Analyst 
Maxwell 

lla  

2.0 

0.21 

126  
Ua  
16a 

2.0                                 0.409 
2.0 
1.0 
2.0                                0.813 
1.0 
2.0 
0.5                                0  990 

0.41 
0.41 
0.42 
0.81 
0.82 
0.80 
1  00 

Swindells 

Swindells 
Maxwell 

2la  
Sugar  

0.5 
1.0 
2.0 
2.0                                0.617 
2.0 
Gram 
0.00421 
0.00421 
0.00421 

1.00 
1.00 
0.98 
0.62 
0.62 
Gram 
0.0046 
0.0042 
0.0040 

Cain 

Cain 
Maxwell 

Maxwell 
Maxwell 
Maxwell 

CARBON  117 

Operating  Suggestions 

l^Stock  barium  hydroxide  solutions  are  conveniently  made  in 
one  to  two  carboy  lots  by  adding  solid  barium  hydroxide  to  the  carboy 
nearly  filled  with  water  (agitating  with  air)  until  the  equivalent 
strength  approaches  5  per  cent  carbon ;  subsequent  additions  can  then 
be  made  by  adding  a  saturated  barium  hydroxide  solution.  Of 
course,  it  is  not  necessary  to  make  up  exactly  to  the  equivalent  of  5 
per  cent  carbon ;  an  approximation  to  this  is  all  that  is  desired.  The 
strength  of  the  solution  is  determined  from  time  to  time  during  the 
standardization  by  running  a  portion  of  the  solution  into  the  cell  and 
measuring  its  resistance.  If  a  set-up  like  that  shown  on  Page  114  is  used 
in  measuring  the  resistance,  it  is  not  necessary  to  remove  the  carboy 
from  the  shelf  or  to  break  any  of  the  connections  during  these  opera- 
tions. If  it  is  desired  to  economize  in  the  use  of  barium  salt,  the  waste 
solution  in  reservoir  G  can  be  brought  up  to  strength  as  described, 
after  first  decanting  it  off  from  the  barium  carbonate  that  has  settled 
out.  A  still  further  economy  can  be  effected  by  drying  and  calcining 
to  oxide  the  precipitated  barium  carbonate;  this  oxide  can  then,  of 
course,  be  used  again. 

2 — The  cell  constants  should  be  checked  from  time  to  time. 
This  may  be  done  (1)  by  turning  standard  samples,  or  (2)  by  determin- 
ing the  resistance  of  a  N/ 10  solution  of  pure  potassium  chloride. 
This  solution  should  be  prepared  on  the  day  it  is  used,  since  it  has  been 
found  that  stock  solutions  change  during  the  course  of  this  work. 
Table  V  shows  the  resistivities  at  various  temperatures  of  N/10 
potassium  chloride  solutions.  The  cell  constant  is  computed  from  the 
formula  R  =  NS,  or  N  =  R/S,  where  R  is  the  observed  resistance, 
N  the  cell  constant,  and  S  the  resistivity,  taken  from  Table  V,  for  the 
same  temperature.  If  a  change  in  cell  constant  has  taken  place  it  is 
most  probable  that  the  electrodes  need  replatinizing.  Directions  for 
this  are  given  below.  If  Method  1  is  used,  any  marked  deviation 
from  the  correct  carbon  value  of  the  standard  steel  may  be  due  to  a 
change  in  the  cell  constant,  and  this  should  then  be  checked  by  Method 
2,  unless  the  error  in  the  carbon  determination  is  suspected  to  be  due 
to  some  other  cause.  In  the  present  work  no  deviation  of  cell  con- 
stants has  been  observed  until  after  several  months'  use,  and  then  the 
change  is  sudden  and  erratic.  When  the  cell  constant  changes  it 
should  be  brought  back  to  the  original  value  by  the  methods  already 
described  under  the  heading  "The  Absorption  Apparatus." 

3 — If  the  absorption  vessels  are  not  to  be  used  for  some  time  they 
should  be  cleaned  with  hydrochloric  acid  (not  over  2  to  3  per  cent 


118  CARBON 

HC1)  followed  by  distilled  water.  Extreme  care  should  be  taken  that 
none  of  the  hydrochloric  acid  or  chlorides  enters  the  reservoir  for 
waste  barium  hydroxide  solution,  if  this  is  to  be  used  again. 

4 — To  platinize  the  electrodes,  the  cap  carrying  them  is 
removed  from  the  cell  and  they  are  first  cleaned  with  sulfuric  acid  and 
chromic  acid  mixture  followed  by  distilled  water.  Then  they  are 
immersed  in  a  vertical  position  in  a  solution  made  of  100  g.  water, 
3  g.  chloroplatinic  acid,  and  0.02  to  0.03  g.  lead  acetate.  Current 
is  passed  through  the  solution  by  connecting  the  electrodes  to  three 
dry  batteries  in  series;  the  current  is  passed  for  5  min.,  reversing 

TABLE  V — Specific  Resistivity  of    N/IQ  KC1  Solution  at  Various 

Temperatures     (from    Landolt-Bornstein     Physickalish- 

Chemische  Tabellen,  4th  Ed.,  Page  1117). 

Temperature  Resistance 

Deg.  C.  Ohms 

15.0  95.42 

16.0  93.28 

17.0  91.32 

18.0  89.37 

19.0  87.49 

20.0  85.69 

21.0  83.96 

22.0  82.30 

23.0  80.71 

24.0  79.11 

25.0  77.64 

26.0  76.16 

27.0  74.79 

28.0  73.42 

29.0  72.10 

30.0  70.82 

31.0  69.59 

32.0  68.40 

33.0  67.20 

34.0  66.09 

35.0  64.98 

«very  half  minute.  Finally,  an  auxiliary  platinum  electrode  is  in- 
troduced and  current  passed  with  this  as  anode  for  another  2  min., 
after  which  the  electrodes  are  washed  thoroughly  with  distilled  water 
and  are  then  ready  for  use. 

Summary     ^ 

I — This  paper  describes  the  fundamental  principles  of  a  method  for 
determining  carbon  dioxide  by  absorbing  it  in  barium  hydroxide  solution 
and  measuring  the  resistance  change  of  the  solution  in  relation  to  its 
concentration. 

II — A  suitable  absorption  vessel  with  electrolytic  resistance  cell 
incorporated  is  illustrated  and  described. 


CARBON  119 

III — Resistance  measurements  of  barium  hydroxide  solutions 
varying  in  connection  from  3.08  g.  Ba(OH)2  per  1.  to  42.25  g.  Ba(OH)2 
per  1.  were  determined  approximately,  and  determinations  accurate 
within  0.01  ohm  were  made  of  the  resistances  of  twelve  different 
solutions  varying  from  5.820  g.  Ba(OH)2  per  1.  to  7.300  g.  Ba(OH)2 
(OH)2perl. 

IV — Temperature  coefficients  of  resistance  of  these  twelve 
solutions  were  determined  in  the  range  20.00°  to  30.00°  C. 

V — Based  on  the  measurements  of  resistance  of  the  barium 
hydroxide  solutions,  solutions  with  concentrations  varying  between 
5.820  g.  Ba(OH)2  per  1.  and  7.300  g.  Ba(OH)2  per  1.  were  chosen  as 
most  suitable  for  this  method. 

VI — Special  resistance-measuring  apparatus  was  developed  which 
simplified  these  measurements  by  dispensing  with  tuned  telephones, 
high  frequency  generators,  and  balanced  inductances  and  capacities. 

VII — A  convenient  nomographic  method  of  applying  necessary 
temperature  corrections  to  resistance  measurements  was  developed. 

VIII — The  method  permits  of  accurate  determinations  of  carbon 
in  steel  (i.  e.,  within  0.01  per  cent  carbon),  by  the  direct  combustion 
method  in  4J/2  to  5  min. 

A  cknowledgment 

The  authors  desire  to  acknowledge  the  work  of  Mr.  H.  E.  Cleaves, 
former  member  of  the  Chemistry  Division  of  the  Bureau  of  Standards, 
who  carried  out  some  preliminary  measurements,  and  the  assistance 
of  Messrs.  Silsbee,  Agnew,  and  Isler  of  the  Electrical  Division  of  the 
Bureau,  who  co-operated  effectively  in  the  selection  of  a  suitable 
alternating  current  galvanometer.  The  Leeds  and  Northrup  Com- 
pany also  co-operated  fully  by  constructing  .and  loaning  electrical 
measuring  apparatus  for  experimental  wTork  and  by  finally  building 
in  practical  form  the  apparatus  that  was  developed. 

Bureau  of  Standards 
Washington,  D.  C. 


120 


CARBON 


CHROMIUM  121 


CHROMIUM 

METHOD  FOR  CHROMIUM  AND  VANADIUM 

IN  CHROME-VANADIUM  STEELS 

BUREAU  OF  STANDARDS 

Dissolve  the  sample  (2.00  g.)  contained  in  a  300  cc.  covered  Erlen- 
meyer  flask  in  10  cc.  of  30%  sulphuric  acid  and  20  cc.  of  water.  Di- 
lute to  200  cc.  with  boiling  water  and  add  from  a  burette  sodium 
bicarbonate  solution  (80  g.  per  1.)  until  a  permanent  precipitate  is 
formed,  and  then  4  cc.  more.  Boil  one  minute,  allow  to  settle  and 
filter  rapidly.  Wash  4  to  5  times  with  boiling  water.  (The  nitrate 
may  be  used  for  the  determination  of  the  manganese.) 

Ignite  the  residue  on  the  filter  paper  in  an  iron  crucible  and  fuse 
with  10  to  12  times  its  volume  of  sodium  peroxide.  Dissolve  the 
melt  by  immersing  in  100  cc.  of  water,  remove  the  crucible  and  destroy 
any  remaining-  peroxide.  (This  may  be  accomplished  by  heating 
for  one-half  hour  on  the  steam  bath.) 


Filter  into  a  200  cc.  graduated  flask  and  fill  up  to  the  mark 
water.  Acidify  100  cc.  of  this  solution  with  sulphuric  acid  and  titrate 
with  ferrous  sulphate  and  permanganate.  The  chromium  may  be 
calculated  from  the  number  of  cc.  of  permanganate  equivalent  to  the 
chromium  reduction. 

Neutralize  the  rerriaining  100  cc.  of  solution  with  sulphuric  acid 
and  then  add  3  cc.  more  of  sulphuric  acid  (sp.  gr.  1.84).  Heat  the 
solution  to  boiling  and  reduce  in  a  Jones  reductor  allowing  the  reduced 
solution  to  flow  into  a  ferric  alum  solution  contained  in  the  receiving 
flask.  Remove  the  receiving  flask,  decolorize  the  ferric  iron  by 
adding  a  few  cc.  of  phosphoric  acid  anol  titrate  hot  with  potassium 
permanganate.  Subtract  from  the  permanganate  used  one-third 
the  number  of  permanganate  equivalent  to  the  chromium  reduction 
in  the  first  100  cc.  aliquot.  The  remainder  represents  the  amount  of 
permanganate  required  to  oxidize  the  vanadium  from  V2O2  to  V2O5. 

In  passing  through  the  Jones  reductor  the  chromium  is  reduced 
to  CrO  and  the  vanadium  to  V2O2.  These  react  with  the  ferric 
alum  more  or  less  completely  reducing  some  of  it  to  the  ferrous  con- 
dition. The  permanganate  oxidizes  the  chromium  to  the  Cr2O3 
condition,  the  vanadium  to  V2O5  and  the  iron  to  the  ferric  condition. 


122  CHROMIUM 

DETERMINATION  OF  CHROMIUM 

BY  BISMUTHATE  METHOD 

This  method  is  based  on  the  fact  that  chromium  and  manganese 
are  oxidized  by  sodium  bismuthate  in  either  nitric  acid,  sulphuric  acid, 
or  a  mixture  of  nitric  and  sulphuric  acids. 

Nitric  acid  alone  is  generally  used,  and  only  in  rare  instances  will 
it  be  necessary  to  add  sulphuric  acid  to  facilitate  the  solution  of  the 
metal.  Some  manganese  is  oxidized  to  permanganic  acid,  which  is 
decomposed  by  boiling,  forming  nitrate  of  manganese  and  manganese 
dioxide. 

The  manganese  dioxide  is  removed  by  nitration  through  asbestos, 
washing  the  asbestos  well  with  a  3%  solution  of  nitric  acid.  If  any  chro- 
mium is  present  it  will  be  indicated  by  a  yellow  color  in  the  nitrate. 

Dissolve  3  grams  of  the  sample  in  a  mixture  of  70  cc.  of  water 
and  30  cc.  of  nitric  acid,  (1.42  Sp.  Gr.).  Boil  until  metal  is  in  solution. 
Cool  slightly  and  add  2  grams  of  sodium  bismuthate,  taking  care  to 
wash  all  bismuthate  from  the  neck  of  the  flask. 

Boil  for  15  minutes,  or  until  permanganic  acid  is  decomposed. 
Filter  with  suction  on  asbestos  supported  by  a  tuft  of  glass  wool  in  a 
3"  glass  funnel.  Wash  with  3%  nitric  acid.  Cool  to  tap  water 
temperature  and  dilute  to  500  cc.  with  distilled  water.  Add  a 
measured  excess  of  ferrous  ammonium  sulphate  solution  until  free 
from  yellow  tints.  Titrate  the  excess  with  standard  permanganate 
to  faint  pink  color  that  persists  for  30  seconds. 

Titrate  with  permanganate  50  cc.  of  ferrous  ammonium  sulphate 
containing  the  same  amount  of  acid  and  water  as  the  test. 

The  amount  of  ferrous  ammonium  sulphate  oxidized  by  the 
chromic  acid  and  measured  in  terms  of  permanganate  is  multiplied 
by  the  iron  factor  x  .31,  or  1  cc.  of  tenth  normal  potassium  permanga- 
nate equals  .00173  gram  of  chromium. 

The  ferrous  ammonium  sulphate  is  prepared  by  dissolving  50 
grams  of  the  salt  in  2  liters  of  10%  by  volume  of  sulphuric  acid.  When 
this  strength  solution  is  used,  1  cc.  will  equal  about  J/2  cc.  of  tenth 
normal  permanganate. 

The  following  table  indicates  the  accuracy  of  the  method,  showing 
in  some  instances  a  very  small  percentage  of  chromium  in  the  presence 
of  a  very  high  percentage  of  manganese: 

Chromium  Added                              Chromium  Found  Manganese 

1.44  1.42  .67 

1.44  1.48  .01 

.37  .37  .38 

.33  .35  .55 

.29  .31  .75 

.24  .26  .95 

.12  .11  1.30 

.04  .04  1.90 


CHROMIUM  AND  VANADIUM  123 

DEMOREST1  METHOD  FOR  THE  DETERMINATION  OF 
CHROMIUM  AND  VANADIUM 

Dissolve  2  grams  of  the  sample  in  a  400  cc.  flask  by  a  mixture  of 
12  cc.  of  strong  sulphuric  acid  and  50  cc.  of  water,  heat  the  flask  until 
solution  is  complete,  set  it  off  the  hot  plate  and  add,  very  cautiously, 
25  cc.  of  nitric  acid,  (1.42  Sp.  Gr.)  The  iron  is  immediately  oxidized 
to  the  ferric  state  with  the  evolution  of  much  nitrous  fumes.  Heat 
the  solution  to  boiling  until  the  brown  fumes  are  all  driven  off,  then 
set  the  flask  off  the  hot  plate  and  add  sodium  bismuthate  until  every- 
thing in  solution  is  oxidized  and  the  manganese  appears  as  perman- 
ganic acid  and  does  not  disappear  on  shaking.  Dilute  the  solution 
to  200  cc.,  add  a  little  more  sodium  bismuthate,  and  boil  the  solution 
for  20  minutes  to  decompose  the  permanganic  acid  to  manganese 
dioxide.  Cool  the  solution  by  adding  50  cc.  of  water  and  filter  through 
asbestos.  Then  make  the  volume  up  to  300  cc.  and  cool  to  tap-water 
temperature,  when  it  is  ready  for  the  chromium  titration  after  the 
addition  of  5  cc.  of  syrupy  phosphoric  acid  to  decolorize  the  iron. 

To  titrate,  run  in  TV/100  ferrous  sulphate  solution  until  all 
chromium  and  vanadium  are  reduced.  This  can  be  discerned  by 
testing  a  drop  on  a  white  plate  with  a  drop  of  ferricyanide.  If  a  blue 
color  is  obtained  enough  ferrous  sulphate  has  been  added.  Add 
TV/100  permanganate  until  a  pink  color  appears  which  persists  on 
shaking,  then  add  a  few  more  cubic  centimeters  of  TV/100  permanganate 
and  stir  the  solution  for  a  minute.  Then  add  TV/100  ferrous  sulphate 
until  the  pink  just  disappears.  The  total  ferrous  sulphate  minus  the 
permanganate  multiplied  by  0.0001733  equals  the  chromium  present. 

Add  to  the  solution  enough  ferrous  sulphate  to  reduce  the  vana- 
dium and  to  have  a  considerable  excess,  mix  the  solution  and  add  about 
1  gram  of  20-mesh  ignited  natural  manganese  dioxide.  Shake  the 
solution  until  a  test  with  ferricyanide  on  a  white  plate  shows  that  all 
ferrous  iron  has  been  oxidized.  Then  filter  through  asbestos  (using 
suction)  and  titrate.  Add  TV/100  permanganate  until  a  persistent 
pink  color  is  obtained,  then  add  several  more  cubic  centimeters  and 
shake  the  solution  for  a  minute.  Now  add  N / 100  ferrous  sulphate 
until  the  pink  color  just  disappears.  The  permanganate  used  minus  the 
ferrous  sulphate  used  multiplied  by  0.00051  equals  the  vanadium 
present. 

NOTES  ON  THE  PROCESS.  The  bismuthate  oxidizes  the 
chromium,  vanadium  and  manganese  to  chromic  acid,  vanadic  acid 
and  permanganic  acid.  Boiling  destroys  the  permanganic  acid  and 

1  The  Journal  of  Industrial  and  Engineering  Chemistry,  December,  1912. 


124  CHROMIUM  AND  VANADIUM 

manganese  dioxide  precipitates  and  is  filtered  off.  When  ferrous 
sulphate  is  added,  chromic  and  vanadic  acids  are  reduced  to  trivalent 
chromium  and  quadrivalent  vanadium;  then  when  permanganate  is 
added  vanadium  only  is  oxidized  back  and  the  ferrous  sulphate  minus 
the  permanganate  measures  the  chromium. 

Vanadium  is  again  reduced  by  ferrous  sulphate  (not  measured), 
the  excess  of  ferrous  sulphate  oxidized  by  manganese  dioxide,  leaving 
the  vanadium  ready  to  be  titrated. 

The  following  are  some  results  obtained  by  the  above  method: 

PERCENTAGES  CHROMIUM 

Present  Found 

0.078  0.086 

0.155  0.160 

0.155  0.157 

0.233  0.236 

0.078  0.078 

0.233  0.225 

3.100  3.095 

A  blank  must  be  run  on  the  chromium  determination,  as  a  small 
amount  of  MnO2  persists  in  solution  and  runs  uniformly  the  same. 


COPPER  125 

DETERMINATION  OF  COPPER  BY 
COLORIMETRIC  METHOD 

Dissolve  10  grams  of  drillings  in  a  mixture  of  25  cc.,  1.84  sp.  gr., 
sulphuric  acid  and  250  cc.  of  distilled  water,  using  a  500  cc.  flask. 
Heat  carefully  until  the  borings  have  dissolved,  dilute  to  400  cc.  with 
distilled  water  and  add  0.5  gram  zinc  sulphide*,  cork  flask  for  a  few 
minutes,  filter  on  an  11  cm.  paper,  wash  the  residue  with  hydrogen 
sulphide  water,  open  paper  against  side  of  funnel,  add  20  cc.  of  hot 
nitric  acid,  1.18  sp.  gr.,  to  the  residue  on  the  paper,  allowing  the  solu- 
tion to  run  into  the  flask  in  which  the  borings  had  been  dissolved. 

Wash  the  paper  with  2%  nitric  acid  solution,  evaporate  the 
filtrate  to  about  15  cc.,  remove  from  hot  plate  and  add  ammonia 
water  (1:3)  just  sufficient  to  precipitate  the  ferric  hydroxide. 

Filter  into  a  100  cc.  Nessler  tube  and  wrash  with  hot  water.  The 
presence  of  copper  will  be  indicated  by  the  blue  color  of  the  filtrate 
from  the  ferric  hydroxide.  To  another  Nessler  tube  add  about  50 
cc.  of  distilled  water  and  5  cc.  of  (1 :3)  ammonia  water.  Then  add 
from  a  burette  a' standard  copper  solution  until  the  colors  match  when 
diluted  to  the  same  volume. 

Modification.  It  is  sometimes  found  convenient  to  modify  the 
method  for  determining  copper.  After  determining  the  sulphur 
by  the  evolution  method  the  hydrochloric  acid  solution  can  be  used  for 
the  determination  of  this  element  as  follows: 

The  solution  from  the  determination  of  sulphur  is  neutralized 
with  ammonia  until  there  is  a  slight  precipitate  of  ferrous  hydroxide. 
Acidify  with  5  cc.  of  hydrochloric  acid,  heat  to  boiling  point,  add  0.5 
gram  zinc  sulphide,  when  dissolved  dilute  to  400  cc.  with  distilled 
water,  cork  flask  for  a  few  minutes,  and  filter  rapidly  on  an  11  cm. 
paper.  Wash  with  hydrogen  sulphide  water  and  finish  the  determina- 
tion as  previously  described. 

Caution  The  success  of  the  colorimetric  method  for  determining 
copper  depends  upon  carefully  following  each  detail.  Some- 
times a  green  color  will  be  obtained  instead  of  a  blue.  This  is 
usually  due  to  the  use  of  too  much  ammonia  and  can  be  corrected 
by  acidifying  the  green  solution  with  dilute  sulphuric  acid  (1:1)  and 
then  making  the  solution  faintly  ammoniacal. 

*  The  use  of  zinc  sulphide  was  suggested  to  us  by  W.  F.  Clark,  Dunston  on  Tyne,  England. 


126  COPPER 

Standard  Copper  Solution.  The  standard  copper  solution  can  be 
prepared  by  dissolving  7.856  grams  of  crystallized  copper  sul- 
phate in  about  200  cc.  of  distilled  water  and  10  cc.  of  nitric  acid, 
1.42  sp.  gr.,  and  diluting  to  2  liters.  This  solution  can  also  be 
prepared  by  dissolving  2  grams  of  copper  in  20  cc.  of  dilute  nitric  acid, 
and  diluting  to  2  liters.  Each  cubic  centimeter  represents  0.01  per 
cent  copper  when  using  10  grams  for  analysis. 


COPPER  127 

DETERMINATION  OF  COPPER  BY 
IODIDE  METHOD 

The  colorimetric  method  for  determining  copper  is  not  sufficiently 
accurate  when  this  element  is  in  excess  of  .15  per  cent.  When  such 
is  the  case  proceed  as  outlined  for  the  determination  of  this  element 
by  the  colorimetric  method  to  the  point  where  dilute  ammonia  is 
added  to  precipitate  the  ferric  hydroxide.  Instead  of  filtering  into 
a  100  cc.  Nessler  tube  use  a  250  cc.  beaker  for  this  purpose. 

After  washing  a  few  times  with  hot  water  dissolve  the  ferric 
hydroxide  with  hot  dilute  hydrochloric  acid,  allowing  the  solution  to 
run  into  the  flask  in  which  the  original  precipitation  was  made,  wash 
a  few  times  with  hot  water,  add  ammonia  water  1:3  just  sufficient 
to  precipitate  the  ferric  hydroxide  and  leave  a  very  slight  excess  of 
ammonia  present,  heat  to  boiling,  filter,  and  allow  the  filtrate  to  flow 
into  the  250  cc.  beaker  containing  the  major  portion  of  the  copper. 

Add  5  cc.  of. sulphuric  acid,  1.84  sp.  gr.,  evaporate  on  hot  plate 
to  dense  fumes,  cool,  add  20  cc.  of  water,  make  slightly  alkajine  with 
ammonia,  boil  off  excess  ammonia  then  neutralize  with  glacial  acetic 
acid  adding  5  cc.  in  excess,  cool  and  add  5  grams  of  potassium  iodide 
crystals,  then  a  few  cubic  centimeters  of  starch  solution,  and  titrate 
with  TV/20  sodium  thiosulphate  solution  to  the  disappearance  of  the 
blue  color.  (12.4  grams  per  liter,  1  cc.  thiosulphate  equals  .00318 
gram  copper). 

The  thiosulphate  can  be  conveniently  standardized  by  using  25 
cc.  of  the  standard  copper  sulphate  solution  described  in  the  Colorimet- 
ric Method  for  determining  copper,  adding  the  same  reagents,  and 
titrating  under  the  same  conditions  as  described  in  the  regular  method. 

If  preferred  the  thiosulphate  can  be  standardized  by  dissolving 
5  grams  of  potassium  iodide  in  500  cc.  of  water,  adding  25  cc.  concen- 
trated hydrochloric  acid,  then  exactly  25  cc.  of  standardized  N/ 10 
potassium  bichromate  solution.  Add  starch  solution  and  titrate 
with  the  thiosulphate  solution  to  the  disappearance  of  the  blue  color. 
Each  cc.  of  N/ 10  potassium  bichromate  solution  equals  .00636  gram 
copper. 

Standard  Starch  Solution.  The  starch  solution  used  in  this  method 
is  prepared  as  described  under  the  determination  of  sulphur  in  iron 
and  steel,  Page  191. 


128 


COPPER 


Limestone  is  used  in  Open  Hearth  furnaces  for  fluxing  the  impurities  in  the  manu- 
facture of  ARMCO  Ingot  Iron  products.     This  shows  method 
of  sampling  each  carload  received 


HYDROGEN  129 

DETERMINATION  OF  HYDROGEN 

The  method  for  determining  hydrogen  by  heating  the  metal  in 
a  partial  vacuum  and  measuring  the  liberated  hydrogen  is  very  la- 
borious. The  hydrogen  existing  as  ammonia  would  not  be  estimated 
by  the  above  method. 

Our  method  is  based  on  the  fact  that  hydrogen  is  liberated  by 
heating  the  metal  to  a  red  heat  in  an  atmosphere  of  oxygen.  The 
hydrogen  is  oxidized  to  water,  which  is  absorbed  in  phosphoric  anhy- 
dride. 

The  apparatus  used  consists  of  a  12"  gas  blast  furnace  for  burning 
the  sample,  and  a  12"  electric  furnace  for  purifying  the  oxygen  gas. 

The  oxygen  gas  is  passed  through  a  M"  silica  tube  (T-2)  at  the 
rate  of  25  cc.  per  minute.  This  furnace  is  heated  to  about  750°  C., 
which  is  sufficient  to  purify  the  oxygen  gas.  The  impurities  are  ab- 
sorbed by  passing  the  gas  first  into  a  solution  of  caustic  potash  (K-2) 
and  then  through  a  bottle  containing  caustic  soda  (K),  and  finally 
through  a  tube  containing  phosphoric  anhydride  opened  up  in  glass 
wool  (P-l). 

The  purified  oxygen  gas  then  enters  the  rw'  silica  tube  (T-l) 
where  it  combines  with  the  hydrogen  which  is  liberated  from  the 
metal,  thus  forming  water  which  is  absorbed  in  a  4"  glass  stop- 
cock U  tube  containing  phosphoric  anhydride  opened  up  with 
glass  wool  (P-2).  This  weighed  4"  U  tube  is  connected  with  the  7A" 
silica  tube  (T-l),  after  the  sample  has  been  placed  in  the  combustion 
tube.  The  weighed  U  tube  is  then  connected  with  bottle  containing 
sulphuric  acid  (Cone.). 

The  combustion  tube  is  heated  to  a  temperature  not  to  exceed 
800°  C.,  as  a  higher  temperature  and  a  higher  rate  of  oxygen  than 
prescribed  may  generate  enough  heat  to  damage  the  apparatus. 
The  oxygen  passes  through  the  entire  apparatus  at  the  rate  of  25  cc. 
per  minute  for  30  minutes,  and  from  10  to  40  grams  of  drillings  are 
used  for  a  determination. 

After  the  test  is  complete  there  should  be  some  metal  wrhich  has 
not  been  oxidized,  as  it  has  been  found  unnecessary  to  oxidize  all  of 
the  metal  in  obtaining  accurate  results. 

.  After  having  ignited  the  sample  for  30  minutes,  the  weighed  U 
tube  (P-2)  is  disconnected,  and  connected  with  an  aspirator  for  the 
purpose  of  replacing  the  oxygen  in  the  tube  with  dry  air. 


130 


HYDROGEN 


HYDROGEN  131 

A  suitable  aspirator  for  this  purpose  consists  of  a  one  gallon 
aspirator  bottle  filled  with  water  connected  with  absorbing  tubes 
as  shown  in  photograph  of  apparatus  for  the  determination  of  oxygen 
and  carbon  monoxide  in  iron  and  steel  on  page  158. 

The  increased  weight  of  the  U  tube  which  is  due  to  the  water 
which  has  been  absorbed  is  multiplied  by  .11190  then  by  100,  and 
divided  by  the  weight  of  sample  taken.  This  gives  the  percentage 
of  hydrogen  in  the  metal. 


132 


HYDROGEN 


Chemist  making  a  calorimeter  test  on  coal  to  determine  its  heating  value 


IRON  133 

GRAVIMETRIC  DETERMINATION 
OF  IRON 

Dissolve  about  1  gram1  of  the  sample,  accurately  weighed,  in  a 
600  cc.  Jena  glass  beaker2,  on  the  water  bath,  using  25  cc.  of  a  10% 
solution  of  hydrochloric  acid. 

When  solution  is  complete,  add  200  cc.  of  distilled  water,  heat  on 
water  bath  to  about  80°  C.,  and  pass  a  moderate  current  of  hydrogen 
sulphide  gas  through  the  solution  for  20  minutes. 

Remove  from  water  bath,  add  200  cc.  more  of  cold  distilled  water, 
and  continue  the  stream  of  hydrogen  sulphide  for  another  20  minutes, 
or  until  the  solution  is  cold.  Filter  from  the  precipitate  and  wash 
thoroughly  with  hydrogen  sulphide  water  containing  a  small  amount 
of  hydrochloric  acid3,  collecting  the  nitrate  in  an  800  cc.  Jena  glass 
beaker2. 

Test  the  residue  for  iron4.  Evaporate  the  nitrate  on  the  water 
bath  until  the  volume  is  reduced  to  about  200  cc.  and  all  the  hydrogen 
sulphide  is  driven  off.  Then  add  5  cc.  of  concentrated  nitric  acid 
and  10  cc.  of  concentrated  hydrochloric  acid0,  and  heat  to  about  90° 
C.,  on  the  water  bath  and  add  a  slight  excess  of  warm  dilute  ammonia6. 

Allow  the  precipitate  to  settle,  decant  through  a  15  ctm.  ashless 
filter,  transfer  the  precipitate  to  the  filter7  and  wash  with  boiling 
water  until  5  cc.  of  the  washings  give  no  opalescence  with  silver 
nitrate8.  (Collect  the  filtrate  and  the  first  washings  in  a  clean  800 
cc.  beaker  and  reserve  for  determination  of  manganese).  . 

Dry  the  ferric  hydroxide  precipitate  at  95-100°  C9.,  and  then 
separate  as  perfectly  as  possible  from  the  filter  paper,  in  a  room  free 
from  draught,  placing  the  dry  ferric  hydroxide  in  a  small  porcelain 

dish  on  a  white  glazed  paper.       Cover  the  porcelain  dish  with  a  watch 
glass  and  then  ignite  the  filter  paper  in  a  weighed  porcelain  crucible. 

Transfer  the  precipitate  from  the  porcelain  dish  to  the  crucible; 
cover  with  a  platinum  cover  and  ignite  for  10  minutes  over  a  Bunsen 
burner;  remove  the  cover,  incline  the  crucible  slightly  and  ignite  for 
another  10  minutes.  Place  in  desiccator,  cool  and  weigh.  Repeat 
the  ignition  until  the  weight  remains  constant,  taking  care  not  to  heat 
more  than  a  few  minutes  at  a  time  and  not  at  too  high  temperature10. 

In  the  meantime  evaporate  the  filtrate  for  the  determination  of 
manganese,  to  about  200  cc.  Add  ammonia,  heat  to  boiling  and  pre- 
cipitate the  manganese  with  a  saturated  solution  of  bromine.  Boil 


134  IRON 

for  a  few  minutes,  filter  on  a  small  ashless  filter,  ignite  and  weigh  as 
Mn3O4.  This  weight  subtracted  from  the  weight  of  Mn3O4  in  the 
sample,  calculated  from  the  total  manganese,  gives  the  amount  of 
Mn3O4  in  the  ferric  oxide. 

To  determine  silica  in  the  ignited  precipitate,  transfer  this  to  a 
small  platinum  dish  and  digest  with  concentrated  hydrochloric  acid 
on  the  water  bath  and  evaporate  to  dry  ness11.  Redissolve,  dilute 
with  hot  water  and  filter  from  the  silica  on  a  small  ashless  filter. 
Wash  with  hot  dilute  hydrochloric  acid  and  hot  water  until  the  silica  is 
free  from  iron. 

Ignite  in  a  platinum  crucible,  cool  and  weigh,  and  then  evaporate 
with  2  drops  of  sulphuric  and  1  cc.  of  hydrofluoric  acid;  ignite,  cool 
and  weigh.  The  difference  between  the  two  weighings  then  repre- 
sents the  amount  of  silica  in  the  ferric  oxide12. 

The  total  amount  of  silica,  manganese  oxide,  chromic  oxide, 
phosphoric  acid  and  alumina  (calculated  from  analysis),  subtracted 
from  the  weight  of  impure  ferric  oxide,  gives  the  weight  of  pure 
Fe2O3,  which  contains  69.94%  iron  (Fe  =  55.84). 

NOTES  ON  GRAVIMETRIC  DETERMINATION 
OF  IRON 

(1).  By  employing  a  power-driven  centrifuge  of  large  capacity 
the  washing  of  precipitate  can  be  perfectly  and  quickly  performed 
largely  by  decantation,  thereby  enabling  the  operator  to  use  a  sample 
as  large  as  5  grams. 

(2).  Beakers,  funnels,  watch  glasses  and  glass  rods  must  be 
thoroughly  cleaned  with  warm  concentrated  hydrochloric  acid  before 
use,  in  order  to  prevent  any  foreign  iron  from  entering  the  solutions. 

(3).  The  presence  of  acid  is  necessary  to  secure  a  perfect  re- 
moval of  iron  from  the  residue  and  the  filter  paper.  The  hydrogen 
sulphide  removes  the  following  elements:  Silver,  lead,  mercury,  gold, 
platinum,  tin,  antimony,  .arsenic,  copper,  cadmium,  bismuth, 
molybdenum,  tellurium,  selenium,  germanium,  iridium,  osmium, 
palladium,  rhodium,  ruthenium,  tungsten,  vanadium. 

(4).  If  great  accuracy  is  desired,  the  analysis  should  be  rejected 
whenever  more  than  traces  of  iron  are  detected  in  the  sulphide  residue. 

(5).  The  nitric  acid  is  added  to  oxidize  the  iron,  and  the  hy- 
drochloric acid  to  secure  sufficient  ammonium  chloride  to  keep  zinc, 


IRON  135 

cobalt,   nickel  and   part  of  the  manganese  in  solution.        In   nickel 
steels  the  precipitation  should  be  repeated  several  times. 

(6).  A  large  excess  of  ammonia  is  objectionable,  as  it  causes 
some  of  the  iron  to  become  colloidal. 

(7).  Ferric  hydroxide  adheres  to  the  beaker  and  the  glass  rod. 
In  order  to  remove  this  quantitatively,  a  few  drops  of  concentrated 
nitric  acid  are  introduced  into  the  beaker  and  by  means  of  the  glass 
rod  all  ferric  hydroxide  is  easily  brought  in  solution.  After  dilution 
with  water  the  iron  is  reprecipitated  with  ammonia  and  transferred 
to  the  filter.  Nitric  acid  is  used  in  order  to  prevent  introduction  of 
chlorides.  (See  8). 

(8).  When  iron  is  precipitated  with  ammonia,  small  amounts  of 
basic  iron  salts  are  always  thrown  down  with  the  hydroxide.  The 
amount  and  the  composition  of  the  basic  salts  vary  according  to  the 
conditions.  Thus  in  a  solution  of  sulphate  of  iron  larger  amounts  of 
basic  salts  are  formed  than  from  solutions  of  ferric  nitrate  or  chloride. 
In  a  cold  solution  more  basic  salts  are  formed  than  when  the  solution  is 
nearly  boiling,  'and  in  addition  the  ferric  hydroxide  tends  to  assume 
a  colloidal  state,  especially  in  the  presence  of  a  large  excess  of  ammonia. 
Basic  chloride  of  iron  is  volatile  on  ignition,  hence  the  necessity  of 
eliminating  chlorides.  Warm  water  decomposes  chloride  of  iron, 
leaving  the  hydroxide  free  from  chlorine. 

(9).  The  filter  paper  will  become  brittle  if  heated  at  a  tempera- 
ture above  100°  C.  Dry  at  least  10  hours.  Heat  gradually  in 
crucible. 

(10).  When  ferric  oxide  is  ignited  at  too  high  a  temperature, 
some  magnetic  oxide  of  iron  (Fe3O4)  is  always  formed,  causing  low 
results.  The  formation  of  magnetic  oxide  takes  place  much  more 
readily  when  the  ignition  is  performed  in  a  platinum  crucible.  A 
convenient  arrangement  consists  of  placing  a  small  porcelain  crucible 
within  a  covered  platinum  crucible,  whereby  the  contact  with  plati- 
num is  avoided  and  the  danger  of  overheating  greatly  reduced;  at 
the  same  time  the  disadvantage  of  using  a  porcelain  crucible  alone  is 
overcome. 

(11)  If  the  oxide  has  been  heated  to  a  high  temperature  it  is 
difficult  to  dissolve  in  concentrated  hydrochloric  acid.  To  secure 
solution  in  a  reasonable  length  of  time  in  cases  when  the  oxide  has 
been  overheated,  it  is  advisable  to  grind  the  oxide  carefully  in  an 


136  IRON 

agate  mortar  and  then  ignite  it  for  a  minute,  reweigh  and  determine 
the  silica  on  this  portion  and  from  the  result  calculate  the  silica  in  the 
original  amount  of  oxide. 

(12).  In  all  exact  gravimetric  determinations  of  iron,  allowance 
must  be  made  for  silica  in  the  ferric  oxide.  Most  steel  and  iron  contain 
silicon,  and  considerable  amounts  are  always  dissolved  from  the 
glassware  during  the  chemical  operations.  Glass  is  readily  attacked 
by  warm  ammonia.  Part  of  the  silica  is  undoubtedly  derived  from 
the  ammonia  which  ordinarily  has  been  in  contact  with  common  glass. 
Most  of  the  phosphorus  is  evolved  during  the  solution  in  hydrochloric 
acid.  If,  however,  the  sample  contains  more  than  a  few  thousandths 
of  1%  of  phosphorus,  the  ferric  oxide  should  be  analyzed  for  phos- 
phorus. This  can  be  done  in  the  filtrate  from  the  determination  of 
silica,  and  the  amount  found,  figured  to  phosphoric  anhydride,  added 
to  the  other  impurities. 


MANGANESE  137 


MANGANESE 

PERSULPHATE  METHOD  FOR  THE  DETERMINATION 
OF  MANGANESE 

This  method  is  of  more  value  in  the  determination  of  manganese 
in  steel  than  in  pure  American  Ingot  Iron.  However,  with  proper 
care  accurate  results  can  be  obtained  on  American  Ingot  Iron.  The 
method  is  as  follows: 

Dissolve  .5  gram  of  the  sample  in  a  250  cc.  Erlenmeyer  flask 
using  25  cc.  (1.20  Sp.  Gr.)  nitric  acid,  heat  on  water  bath  until  brown 
fumes  are  gone.  Remove  flask  from  the  water  bath  and  add  40  to  50 
cc.  N/ 100  silver  nitrate,  return  flask  to  water  bath  and  heat  to  50  to 
60  degrees  C.  Add  about  2  grams  of  crystallized  ammonium  per- 
sulphate and  maintain  the  solution  at  50  to  60  degrees  C.,  for  a  few 
minutes. 

Cool,  dilute  with  100  cc.  distilled  water  and  titrate  with  sodium 
arsenite  to  pale  green  color. 

It  is  necessary  to  keep  the  temperature  between  50  and  60  degrees 
C.  during  the  few  minutes  required  for  the  perfect  oxidation  of  the 
manganese,  otherwise  results  will  be  erratic,  especially  when  analyzing 
American  Ingot  Iron. 


138 


MANGANESE 


AMERICAN  INGOT  IRON 


Sulphur 

Phosphorus 

Carbon 

Manganese 

Silicon 

Copper 

Oxygen 

Nitrogen 

Iron 


.032 
.008 
.011 
.017 
trace 
.030 
.025 
.003 

99.874 


Microstructure    and   Analysis 


MANGANESE  139 

DETERMINATION  OF  MANGANESE 
BISMUTHATE  METHOD 

This  method  was  perfected  by  Professor  D.  J.  Demorest,  of  the 
Ohio  State  University  and  is  substantially  as  follows: 

Dissolve  1  gram  of  the  sample  in  30  cc.  of  Nitric  Acid  (Sp.  Gr. 
1.13)  and  boil  until  brown  fumes  disappear.  After  cooling  somewhat 
one-half  gram  of  sodium  bismuthate  is  added,  a  little  at  a  time,  until 
the  resulting  permanganic  acid  or  manganese  dioxide  persists  after 
a  few  minutes  boiling.  Now  add  3  cc.  of  a  5%  solution  of  potassium 
nitrite  to  reduce  the  manganese  compounds,  and  boil  the  solution  a  few 
minutes  to  expel  the  nitrous  fumes. 

Cool  to  tap  water  temperature  and  when  cold  add  sodium  bis- 
muthate, a  little  at  a  time,  while  the  solution  is  shaken,  until  about 
}/<?  gram  has  been  added. 

After  settling  a-  few  minutes  the  solution  is  filtered  by  suction 
through  asbestos  on  glass  wool  contained  in  a  3"  funnel. 

The  filter  is  well  washed  with  a  3%  solution  of  nitric  acid  pre- 
pared from  colorless  acid,  and  containing  a  small  amount  of  sodium 
bismuthate  in  suspension.  The  permanganic  acid  is  then  titrated 
with  standard  sodium  arsenite  solution  until  the  pink  tinge  just  dis- 
appears. There  should  not  be  a  brownish  color  at  the  end.  If  there 
is,  it  indicates  insufficient  acid. 

The  sodium  arsenite  is  prepared  by  dissolving  2  grams  of  ar- 
senious  acid  in  a  hot  solution  of  sodium  carbonate,  using  sufficient 
sodium  carbonate  to  completely  dissolve  the  arsenious  acid.  It  is 
then  filtered  through  paper  and  diluted  to  2  liters.  One  cc.  is  ap- 
proximately equal  to  .00025  gram  of  manganese.  The  solution  is 
standardized  against  steel  of  known  manganese  content. 

Important  Details 

(1).  Do  not  filter  immediately  after  the  addition  of  sodium 
bismuthate,  but  let  stand  at  least  one  minute. 

(2).     Keep  the  asbestos  filter  clean  and   level  across  the  top. 

To  clean:  Wash  filter  with  hot  concentrated  nitric  acid,  then 
run  through  the  filter  a  strong  solution  of  potassium  permanganate 
and  finally  wash  clean  with  the  prepared  wash  water  solution. 


140 


MANGANESE 


(3).  Use  care  in  preparing  the  wash  water  solution,  being  sure 
that  it  is  3%  nitric  acid  in  strength  and  contains  a  small  amount  of 
free  sodium  bismuthate  in  suspension. 

A  modification  of  this  method  is  described  by  P.  L.  Robinson  in 
Chemical  News  119,  187-8  (1919).  The  modification  consists  of 
adding  10  cc.  of  ammonium  persulphate  solution  (120  g.  per  liter)  for 
the  preliminary  oxidation  of  the  carbonaceous  matter.  Do  not  re- 
move the  assay  from  the  plate  after  solution,  but  immediately  after 
the  brown  fumes  have  cleared  add  the  ammonium  persulphate;  then 
boil  for  10  minutes  to  decompose  the  excess  of  ammonium  persulphate, 
cool,  oxidize  with  sodium  bismuthate,  filter,  and  titrate  in  the  usual 
manner. 


Taking  samples  of  coal  by  the  Trench  Method.      Three  trenches  being  dug  in  each 
car  of  coal  received.       The  sample  which  is  taken  is  thoroughly  ground 
for  chemical  analysis.       The  control  of  the  quality  of  coal  which 
enters  into  all  of  our  metallurgical  practice  is  one  of  the 
reasons    for    the    regularity    and    uni- 
formity of  the  products  which 
we  manufacture 


MANGANESE  141 

DETERMINATION  OF  MANGANESE 

BY  COLOR 

Dilute  the  solutions  from  color  carbon  determination  to  30  or  40 
cc.  Remove  10  cc.  from  each  with  a  pipette,  place  in  10"xl"  test 
tubes  and  add  to  each  3  cc.  of  nitric  acid  (Sp.  Gr.  1.18).  Bring  to 
boil  and  add  J/o  gram  of  lead  peroxide  (free  from  manganese)  to  each 
and  boil  vigorously  for  3  minutes. 

Cool  and  pour  into  15  cc.  centrifuge  tubes  and  separate  the  un- 
dissolved  lead  peroxide  by  centrifuging  a  few  minutes.  Decant  clear 
solution  into  comparison  tubes  and  dilute  until  colors  match.  If  no 
centrifuge  is  available  the  lead  peroxide  can  be  filtered  out  on  an 
alundum  crucible  or  on  an  ignited  asbestos  filter  of  the  Gooch  or 
cone  type. 


142 


MANGANESE 


^  ^  -?> 

NEWBURYPORT  LINK 


Sulphur 

Phosphorus 

Carbon 

Manganese 

Silicon 

Copper 

Oxygen 

Nitrogen 

Iron 


.014 
.023 
.040 
.008 
.028 
trace 
.027 
.003 

99.867 


After  100  years  service  Microstructure  and  Analysis 


MANGANESE  143 

TEST  TO  INDICATE  WHETHER  METAL  IS 
IRON  OR  STEEL 

In  making  this  test  without  the  use  of  a  balance  the  following 
table  can  be  used  wrhen  metal  is  in  sheet  form  and  the  gauge  is  known. 
These  weights  represent  the  number  of  grams  in  1  square  inch: 

Grams  Grams  Grams 

Gauge           Sq.  Inch  Gauge  Sq.  Inch  Gauge  Sq.  Inch 

12  14.00  17                     7.10  22  4.00 

13  12.00  18                    6.40  23  3.61 

14  10.00  19                     5.66  24  3.20 

15  9.00  20  4.82  25  2.80 

16  8.00  21  4.41  26  2.41 

As  an  illustration,  suppose  we  have  16-gauge  material.  A 
square  inch  weighs  8  grams,  hence  a  strip  /^"xl"  weighs  approximately 
1  gram,  or  /4r/x}x>"  would  also  equal  1  gram.  If  the  sheet  is  gal- 
vanized the  coating  need  not  be  removed  before  making  the  test. 

Take  equal  portions  of  American  Ingot  Iron  and  sample  to  be 
tested,  equal  to  }/£  gram,  and  place  in  separate  10"xl"  test  tubes. 
Add  to  each  tube  15  cc.  1  of  dilute  nitric  acid,  1.18  specific  gravity2. 
Place  a  test  tube  in  holder,  using  care  to  incline  the  tube  away  from 
spectators  while  being  heated  with  an  alcohol  lamp.  The  metal  will 
disappear  in  a  few  minutes,  but  continue  heating  until  no  more  brown 
fumes  are  given  off.  Allow  solution  to  cool  and  heat  the  other  tube 
in  same  manner  and  cool.  The  solutions  can  be  compared  at  this 
point,  the  darker  one  containing  the  highest  percentage  of  carbon. 

To  each  test  add  J/2  gram  sodium  bismuthate3  and  agitate  for  a 
few  minutes.  Then  add  sufficient  water  to  half  fill  the  tubes  and 
mix  thoroughly.  Allow  the  tubes  to  rest  for  several  minutes  until 
the  undissolved  sodium  bismuthate  settles.  By  comparing  the  clear 
solutions,  American  Ingot  Iron  will  show  a  light  pink  color,  while  steel 
will  yield  a  purple  color  due  to  manganese  present. 

1  If  no  graduate  is  available,  the  volume  of  acid  can  be  estimated  by  noting  the  depth  of  1" 
diameter  tube;  each  inch  is  equal  to  about  10  cc. 

2  Nitric  Acid  of  1.18  specific  gravity  can  be  prepared  by  adding  1  part  1.42  specific  gravity  nitric 
acid  to  2  parts  water. 

3  The  amount  of  sodium  bismuthate  that  can  be  placed  on  a  dime  represents  about    H  gram. 


144 


MANGANESE 


-"•- »-j*.  -v 


BESSEMER  STEEL 


Sulphur 

Phosphorus 

Carbon 

Manganese 

Silicon 

Copper 

Oxygen 

Nitrogen 

Iron 


.050 
.100 
.120 
.480 
trace 
.010 
.025 
.010 

99.2O5 


Microstructure  and  Analysis 


MOLYBDENUM  145 


MOLYBDENUM 

THE  DETERMINATION  OF  MOLYBDENUM 
(AND  COPPER)  IN  STEEL 
BUREAU  OF  STANDARDS 

Dissolve  enough  steel  to  give  .06  to  .1  g.  molybdenum,  in  1:3 
nitric  acid.  When  solution  is  complete,  add  10  cc.  of  sulphuric  acid 
and  evaporate  to  fumes.  Cool  and  dilute.  If  the  residue  is  light 
colored  and  evidently  silica  no  filtration  is  required. 

In  case  the  residue  is  dark  colored  or  indicates  tungstic  acid, 
filter  it  off,  ignite  it  carefully  in  platinum,  fuse  the  residue  with  sodium 
carbonate,  thoroughly  extract  the  melt  with  water,  add  two  grams 
tartaric  acid  to  the  filtered  water  extract,  acidify  to  two  per  cent  by 
volume  sulphuric  acid  and  saturate  with  hydrogen  sulphide.  Digest 
one  hour  at  approximately  50°  C.,  filter  off  any  dark  sulphide  and 
wash  with  a  one  per  cent  by  volume  sulphuric  acid  saturated  with 
hydrogen  sulphide  and  containing  a  little  tartaric  acid.  Dissolve  the 
precipitate  in  aqua  regia  and  add  the  resultant  solution  to  the  solution 
of  the  sulphides  which  is  obtained  as  described  below. 

Dilute  the  main  solution  to  200  cc.,  add  o  grams  tartaric  acid  and 
adjust  the  acidity  to  Yf/o  sulphuric  acid  (by  volume).  Pass  in 
hydrogen  sulphide  until  the  iron  is  reduced,  the  molybdenum  (and 
copper)  is  precipitated,  and  the  solution  is  saturated  with  gas.  Digest 
at  50°-60°  for  one  hour  or  longer.  Filter,  preferably  on  a  Gooch, 
and  wash  with  the  wash  water  specified  above.  Dissolve  the  pre- 
cipitate in  aqua  regia,  unite  with  any  recovery  obtained  as  above 
and  reserve  the  solution. 

Occasionally  the  filtrate  from  the  precipitated  sulphides  contains 
some  molybdenum  which  was  not  precipitated  on  account  of  reduction 
of  the  molybdenum.  It  is  desirable  to  test  this  filtrate  as  follows: 
boil  out  most  of  the  hydrogen  sulphide,  oxidize  the  iron  and  molyb- 
denum by  means  of  bromine  water,  boil  out  excess  bromine  and  again 
proceed  with  the  hydrogen  sulphide  precipitation.  In  case  molyb- 
denum sulphide  is  indicated  it  is  to  be  recovered  as  in  the  regular 
procedure  and  added  to  the  reserved  solution. 


146  MOLYBDENUM 

The  reserved  solution  will  contain  the  molybdenum  and  copper 
originally  present  in  the  steel  and  may  contain  a  little  iron.  Treat 
this  solution  with  5  cc.  of  sulphuric  acid  and  evaporate  to  fumes. 
Dilute  and  in  case  the  solution  is  colored  by  reduced  molybdenum, 
oxidize  with  a  little  permanganate  solution.  Then  add  a  10% 
solution  of  sodium  hydroxide  until  in  slight  excess.  Boil,  filter,  and 
wash  with  hot  1%  sodium  hydroxide  solution.  The  insoluble  con- 
tains the  copper  together  with  a  little  iron,  and  the  copper  may  be 
determined  electrolytically. 

The  nitrate  contains  the  molybdenum  and  this  is  most  con- 
veniently determined  as  follows:  acidify  the  solution,  add  sulphuric 
acid  until  it  contains  3%  by  volume,  warm  the  solution  and  reduce 
in  a  Jones'  reductor  containing  a  solution  of  ferric  alum  and  phos- 
phoric acid  in  the  receiver.  The  molybdenum  is  thus  reduced  to  the 
trivalent  condition  in  the  reductor  and  is  partially  oxidized  by  the 
ferric  sulphate  in  the  receiver  with  the  formation  of  an  equivalent 
amount  of  ferrous  sulphate.  Titrate  the  resultant  solution  with 
tenth  normal  permanganate.  The  molybdenum  and  ferrous  sulphate 
are  oxidized  to  their  higher  valencies  by  the  permanganate  and  the 
calculations  are  based  on  complete  reduction  to  Mo2O3  and  subse- 
quent oxidation  to  MoO3. 


NICKEL  147 

BRUNCK'S1  GRAVIMETRIC  DETERMINATION  OF 

NICKEL 

Dissolve  1  gram  of  steel  or  iron  in  a  150  cc.  Erlenmeyer  flask  with 
the  use  of  30  cc.  of  dilute  nitric  acid,  (1.20  Sp.  Gr.).  Boil  until  brown 
fumes  are  expelled.  Place  5  grams  of  pow^dered  citric  acid  in  an 
800  cc.  beaker.  Add  the  solution  in  the  Erlenmeyer  flask  to  the  dry 
citric  acid,  wash  the  flask  thoroughly  with  water,  and  make  the  volume 
in  the  beaker  up  with  water  to  300-500  cc.,  depending  upon  the 
amount  of  nickel  present.  The  higher  the  nickel  the  more  water 
necessary.  Make  faintly  alkaline  with  ammonia,  then  acid  with 
acetic  acid. 

Note:  Acetic  acid  is  preferred  to  hydrochloric  on  account  of  a 
more  perfect  separation  of  nickel  from  manganese  when  manganese 
is  present. 

The  faintly  acetic  acid  solution  is  heated  to  near  the  boiling 
point,  the  beaker  is  removed  from  the  source  of  heat,  and  from  15  to 
25  cc.  (depending  upon  the  amount  of  nickel  present)  of  a  1%  alco- 
holic solution  of  dimethylglyoxime  added.  The  solution  is  then  made 
faintly  alkaline  with  dilute  ammonia,  the  nickel  being  precipitated  as 
scarlet  nickel  glyoxime.  The  solution  is  kept  hot  for  about  1  hour 
and  filtered  on  a  weighed  Gooch  crucible,  washed  thoroughly  with  hot 
water,  and  dried  at  110-120°  C.  for  45  minutes.  This  scarlet  pre- 
cipitate contains  20.31%  nickel.  If  the  percentage  of  nickel  is  low 
we  use  3  grams  of  the  sample  which  we  dissolve  in  50  cc.  of  nitric 
acid  (Sp.  Gr.  1.20).  We  also  use  15  grams  of  citric  acid.  The 
presence  of  chromium  or  cobalt  does  not  interfere  with  the  precipi- 
tation. 

1  Stahl  u.  Eisen;  28  (1)   p.  331;   1908. 


148 


NICKEL 


View  of  milling  machine  showing  milling  of  sheet  bars  for  the  determination  of  oxygen 

and  carbon  monoxide 


NICKEL  149 

DETERMINATION  OF  NICKEL  IN  STEEL 
TITRATION  METHOD 

The  determination  of  nickel  in  steel  can  be  finished  in  less  than 
25  minutes  with  the  use  of  the  method  devised  by  the  Buckeye  Steel 
Casting  Company. 

Dissolve  1  gram  of  steel  or  iron  in  a  150  cc.  Erlenmeyer  flask  with 
the  use  of  30  cc.  of  dilute  nitric  acid,  (1.20  Sp.  Gr.).  Boil  until  brown 
fumes  are  expelled.  Wash  the  solution  into  an  800  cc.  beaker,  add 
20  cc.  of  Citric  Acid  solution.  Make  faintly  alkaline  with  ammonia, 
and  acidify  slightly  with  acetic  acid.  (Acetic  acid  is  preferred  to 
hydrochloric  on  account  of  a  more  perfect  separation  of  nickel  from 
manganese  when  manganese  is  present.)  The  faintly  acetic  acid 
solution  is  heated  to  near  the  boiling  point,  the  beaker  is  removed 
from  the  source  of  heat,  and  from  15  to  25  cc.  (depending  upon  the 
amount  of  nickel  present)  of  dimethylglyoxime  solution  added.  The 
nickel  being  precipitated  as  scarlet  nickel  glyoxime. 

Bring  to  boil  and  filter  immediately  washing  the  precipitate  from 
the  filter  with  the  use  of  hot  water  into  a  250  cc.  beaker.  Dissolve 
the  nickel  glyoxime  in  20  cc.  of  aqua  regia,  bring  to  boil  in  order  to 
decompose  the  glyoxime.  Dilute  with  about  50  cc.  of  cold  water, 
make  faintly  ammoniacal  and  cool  in  ice  water.  Make  solution  up 
to  150  cc.  with  cold  water,  add  10  cc.  of  potassium  iodide  solution,  then 
1  cc.  of  silver-nitrate  solution  and  titrate  with  potassium  cyanide 
solution  (be  sure  to  do  this  under  the  hood  on  account  of  the  poisonous 
nature  of  the  hydrocyanic  acid)  until  the  turbidity  disappears  and  the 
solution  clears. 

The  potassium  solution  cyanide  is  standardized  with  the  use  of 
Bureau  of  Standards  nickel  steel,  or  with  the  use  of  .2  to  .3  grams  of 
nickel  ammonium  sulphate  which  has  been  added  to  one  gram  of  iron  or 
steel  free  from  nickel  and  analyzed  according  to  the  above  method. 
The  following  solutions  are  used  in  the  determination  of  nickel  by  this 
method : 

Potassium  Iodide 

Dissolve  8  grams  of  potassium  iodide  in  one  liter  of  distilled  water. 

Silver  Nitrate  Solution 

Dissolve  5  grams  of  crystallized  silver  nitrate  in  one  liter  of  dis- 
tilled water. 


150  NICKEL 

Potassium  Cyanide  Solution 

Dissolve  13  to  14  grams  of  potassium  cyanide  in  water  and  when 
in  solution  add  5  grams  of  potassium  hydroxide  which  has  also  been 
dissolved  in  water  and  dilute  the  solution  to  one  liter.  Potassium 
cyanide  containing  sulfide  cannot  be  used;  as  it  forms  a  precipitate  of 
silver  sulfide  which  is  not  dissolved  by  potassium  cyanide. 

Dimethylglyoxime  Solution 

Dissolve  20  grams  of  dimethylglyoxime  in  1300  cc.  of  concentrated 
ammonia,  make  the  solution  up  to  2  liters  with  the  use  of  700  cc.  of 
distilled  water. 

Aqua  Regia  Solution 

As  this  acid  decomposes  upon  standing  it  is  desirable  to  make  up 
fresh  solutions  each  day;  mixing  80%  concentrated  nitric  acid  and 
20%  concentrated  hydrochloric  acid. 

Citric  Acid  Solution 

Dissolve  600  grams  of  citric  acid  in  one  liter  of  distilled  water. 

In  standardizing  the  Potassium  Cyanide  Solution  the  blank 
produced  from  1  cc.  of  silver  nitrate  solution  should  be  deducted 
before  determining  the  strength  of  the  potassium  cyanide,  and  this 
blank  amounting  usually  to  .3  cc.  should  be  deducted  from  each  de- 
termination. 

It  will  be  satisfactory  to  determine  the  blank  using  the  same 
amount  of  water  (made  ammoniacal)  as  the  volume  of  a  determination 
(200  cc.)  using  about  10  cc.  of  potassium  iodide  and  1  cc.  of  silver 
nitrate,  titrating  with  potassium  cyanide  until  the  solution  clears. 


NITROGEN  :5l 

NITROGEN 
DETERMINATION  OF  NITROGEN 

We  use  the  Allen  method  perfected  by  Professor  J.  W.  Langley. 
This  method  is  based  on  the  reaction  by  which  the  combined  nitrogen 
in  iron  or  steel  is  estimated  as  ammonia  by  the  solution  of  the  metal 
in  hydrochloric  acid. 

The  reagents  required  are: 

Hydrochloric  Acid  of  1.1  specific  gravity,  free  from  ammonia, 
which  may  be  prepared  by  distilling  pure  hydrochloric  acid  gas  into 
distilled  water  free  from  ammonia.  To  do  this,  take  a  large  flask 
fitted  with  a  rubber  stopper  carrying  a  separatory  funnel  tube  and  an 
evolution  tube.  Place  in  the  flask  strong  hydrochloric  acid,  connect 
the  evolution  tube  with  a  wash  bottle  connected  with  a  bottle  con- 
taining the  distilled  water.  Admit  strong  sulphuric  acid  free  from 
nitrous  acid  to  the  flask  through  the  funnel  tube,  apply  heat  as  re- 
quired, and  distil  the  gas  into  the  prepared  water. 

Test  the  acid  by  admitting  some  of  it  into  the  distilling  apparatus, 
described  further  on,  and  distilling  it  from  an  excess  of  pure  caustic 
soda,  or  determine  the  amount  of  ammonia  in  a  portion  of  hydrochloric 
acid  of  1.1  specific  gravity,  and  use  the  amount  found  as  a  correction. 

Solution  of  Caustic  Soda,  made  by  dissolving  300  grams  of  fused 
caustic  soda  in  500  cc.  of  water,  and  digesting  it  for  24  hours  at  50° 
C.,  on  a  copper-zinc  couple  prepared  by  rolling  together  about  6 
square  inches  each  of  zinc  and  copper  foil. 

Nessler  Reagent.  Dissolve  35  grams  of  potassium  iodide  in  a 
small  quantity  of  distilled  water,  and  add  a  strong  solution  of  mercuric 
chloride  little  by  little,  shaking  after  each  addition,  until  the  red 
precipitate  formed  dissolves.  Finally  the  precipitate  formed  will 
fail  to  dissolve;  then  stop  the  addition  of  the  mercury  salt  and  filter. 
Add  to  the  filtrate  120  grams  of  caustic  soda  dissolved  in  a  small 
amount  of  water,  and  dilute  until  the  entire  solution  measures  1  liter. 
Add  to  this  5  cc.  of  a  saturated  aqueous  solution  of  mercuric  chloride, 
mix  thoroughly,  allow  the  precipitate  formed  to  settle,  and  decant  or 
siphon  off  the  clear  liquid  into  a  glass-stoppered  bottle. 

Standard    Ammonia   Solution.      Dissolve    .0382  gram  of   ammonium 
••   chloride  in  1  liter  of  water.       One  cc.  of  this  solution  will  equal  .01 
milligram  of  nitrogen. 


152  NITROGEN 

Distilled  water  free  from  ammonia.  If  the  ordinary  distilled  water 
contains  ammonia,  redistil  it,  reject  the  first  portions  coming  over,  and 
use  the  subsequent  portions,  which  will  be  found  free  from  ammonia. 
Several  glass  cylinders  of  colorless  glass  of  about  160  cc.  capacity  are 
required. 

The  best  form  of  distilling  apparatus  consists  of  an  Erlenmeyer 
flask  of  about  1500  cc.  capacity,  with  a  rubber  stopper  carrying  a 
separatory  funnel  tube  and  an  evolution  tube,  the  latter  connected 
with  a  condensing  tube,  around  which  passes  a  constant  stream  of  cold 
water.  The  inside  tube  where  it  issues  from  the  condenser  should  be 
sufficiently  high  to  dip  into  one  of  the  glass  cylinders  placed  on  the 
working  table. 

The  determination  of  nitrogen  is  made  as  follows:  Place  40  cc. 
of  the  caustic  soda,  which  has  been  treated  with  the  copper-zinc 
couple,  in  the  Erlenmeyer  flask,  add  500  cc.  of  water  and  about  2 
grams,  20-mesh  zinc  to  prevent  bumping,  and  distil  until  the  dis- 
tillate gives  no  reaction  with  the  Nessler  reagent.  While  this  part 
of  the  operation  is  in  progress,  dissolve  3  grams  of  the  carefully  washed 
drillings  in  30  cc.  of  the  prepared  hydrochloric  acid,  using  heat  if 
necessary.  Transfer  the  solution  to  the  bulb  of  the  separatory  funnel 
tube,  and  when  the  soda  solution  is  free  from  ammonia,  very  slowly 
drop  the  ferrous  chloride  solution  into  the  boiling  solution  in  the  flask. 
When  about  50  cc.  of  water  has  been  collected  in  the  cylinder,  remove 
it  and  substitute  another  cylinder.  Place  1J/2  cc.  of  the  Nessler 
reagent  in  a  cylinder,  dilute  the  distillate  to  100  cc.  with  the  special 
distilled  water  and  pour  it  into  the  cylinder,  containing  the  Nessler 
reagent.  Take  another  cylinder,  place  therein  1^  cc.  of  the  Nessler 
reagent  and  100  cc.  of  the  special  distilled  water  to  which  1  cc.  of  the 
ammonium  chloride  solution  has  been  added,  and  compare  the  colors 
of  the  solutions  in  the  two  cylinders. 

If  the  solution  in  the  cylinder  containing  the  ammonium  chloride 
solution  is  lighter  in  color  than  that  in  the  cylinder  containing  the 
distallate,  place  lj/2  cc.  of  the  Nessler  reagent  in  another  cylinder, 
pour  into  it  100  cc.  of  water  containing  2  or  more  cc.  of  the  ammonium 
chloride  solution,  and  repeat  this  operation  until  the  colors  of  the  solu- 
tions in  the  two  cylinders  correspond  after  standing  about  10  minutes. 
When  about  100  cc.  have  distilled  into  the  second  cylinder,  replace  it 
and  test  as  before.  Continue  the  distillation  until  the  water  comes 
over  free  from  ammonia,  then  add  together  the  number  of  cc.  of 
ammonia  solution  used,  divide  the  sum  by  3,  and  each  .01  milligram 
will  be  equal  to  .001%  of  nitrogen  in  the  steel. 


OXYGEN  153 


OXYGEN 
CARBON  MONOXIDE 

THE  DETERMINATION  OF  OXYGEN  AND  CARBON 
MONOXIDE  IN  IRON  AND  STEEL 

Ledebur1  about  40  years  ago,  proposed  heating  the  borings 
in  an  atmosphere  of  hydrogen  in  order  to  determine  the  oxygen  con- 
tent. The  method  as  proposed  was  too  laborious,  consequently  was 
not  universally  adopted.  He  recommended  a  preliminary  heating 
of  the  borings  in  nitrogen.  Up  until  the  time  Cushman2  published 
his  paper  on  the  determination  of  oxygen  and  showed  that  an  analysis 
could  be  made  in  less  than  an  hour,  very  little  use  had  been  made  of 
the  method  as  proposed  by  Ledebur.  However,  since  Cushman's 
paper  appeared,  a  considerable  amount  of  work  has  been  done  on  this 
subject  by  many  chemists. 

The  Ledebur  method  for  determining  oxygen  is  recognized  as 
having  its  limitations,  but  where  manganese  and  silicon  are  low,  such 
as  in  pure  iron,  we  have  found  the  method  of  great  help  in  main- 
taining a  uniform  product.  We  have  modified  the  Ledebur  method 
so  that  we  determine  the  oxygen  and  carbon  monoxide  in  one  opera- 
tion. 

For  mill  practice  where  samples  can  be  taken  from  bars  they 
should  first  be  cleaned  from  all  mill  scale  or  surface  oxide  with  the 
use  of  an  emery  wheel.  The  sample  should  then  be  placed  in  a  milling 
machine  which  should  be  run  at  very  slow  speed  in  order  to  avoid 
oxidizing  the  millings.  A  light  transverse  cut  should  be  taken  en- 
tirely across  the  bar  and  the  millings  discarded  in  order  to  remove 
any  oxidized  cavities  which  were  not  removed  by  the  emery  wheel. 

The  sample  should  be  the  average  of  the  entire  cross  section  if 
possible,  as  there  is  some  difference  in  gas  content  between  the  interior 
and  exterior  portions  of  bars.  The  sample  must  be  free  from  all  dirt, 
and  samples  should  not  be  ground  in  the  vicinity  where  a  sample  is 
being  milled,  on  account  of  the  danger  of  contamination  from  finely 
divided  particles  of  oxide  of  iron. 

The  millings  should  be  removed  from  the  sample  by  the  use  of 
a  magnet,  and  placed  in  a  dry  glass  stoppered  bottle:  It  is  of  the 
utmost  importance  that  millings  of  uniform  size  be  used  for  analysis, 

1  Leitfaden  fur  Eisenhutten  Laboratories,  Eighth  Edition,   1908,  page  139. 

2  Determination  of  Oxygen  in  Iron  and  Steel,  by  Allerton  S.  Cushman,  Journal  of  Industrial  and 
Engineering   Chemistry,   June,    1911. 


154 


OXYGEN 


OXYGEN  155 

those  passing  a  twenty  mesh  and  remaining  upon  a  forty  mesh  sieve 
being  selected.  The  millings  should  remain  in  the  unstoppered 
bottle  for  half  an  hour  in  a  desiccator  containing  concentrated  sul- 
phuric acid.  A  30-gram  sample  is  placed  in  a  J/2"x^"x6"  platinum 
or  pure  iron  boat,  (For  cast  iron  use  a  porcelain  boat),  which  is  placed 
in  the  %"x30"  silica  tube,  "T". 

In  most  descriptions  for  determining  oxygen  by  the  Ledebur 
method,  hydrogen  is  generated  by  the  action  of  some  acid  upon  zinc 
contained  in  a  Kipp's  generator.  It  has  been  found  that  hydrogen 
so  prepared  contains  considerable  carbon  monoxide  and  carbon 
dioxide,  whereas  hydrogen  produced  by  the  electrolytic  process  and 
stored  in  tanks  is  practically  free  from  these  two  gases,  is  much  easier 
to  handle,  and  is  cheaper. 

APPARATUS  FOR  THE  DETERMINATION  OF  OXYGEN 
AND  CARBON  MONOXIDE  IN  IRON 
AND  STEEL      . 

29 — Tank  of  Electrolytic  Hydrogen. 

E — Electric  Preheating  Furnace — 850°  C. 

T— Silicia  Tube—  Mx30". 

K — -Bottle  containing  sodium  hydroxide  sticks. 

vS — Bottle  containing  concentrated  sulphuric  acid. 

P — Bottle  containing  phosphoric  anhydride  on  glass  wool. 

T! — Silica    tube    7/8"x3Q"   in   which   is   placed    boat    containing 

sample. 

G— Gas  Furnace — Run  at  1000°  C. 

PI — Absorption    Tube  containing  phosphoric  anhydride  opened 

up  with  glass  wool. 

LP — U  Tube  containing  phosphoric  anhydride  used   as  a  trap. 

I — Glass  tube  containing  iodine  pentoxide. 

O — Furnace  heated  by  Bunsen  Burner  to  150°  C. 

B — Meyer  Bulb  containing  barium  hydroxide  solution. 

The  hydrogen  is  passed  through  a  /4"x30"  silica  tube  "T"  con- 
tained in  an  electric  furnace  "E"  heated  to  850°  C.  It  is  then  passed 
through  a  bottle  "K"  containing  sticks  of  sodium  or  potassium  hy- 
droxide, which  removes  water  and  carbon  dioxide,  then  through  a 
wash  bottle  "S"  containing  concentrated  sulphuric  acid,  and  then 
through  a  bottle  "P"  containing  phosphoric  anhydride  opened  up 
with  glass  wool.  It  then  passes  at  the  rate  of  100  cc.  per  minute  into 
the  K"x30"  silica  tube  "T". 


156  OXYGEN 

Place  the  boat  containing  the  millings  in  the  silica  tube  "T",  and 
insert  stopper  which  is  connected  with  a  weighed  U  tube  "P",  con- 
taining phosphoric  anhydride  opened  up  with  glass  wool.  This  "U" 
tube  is  conneceted  with  a  short  length  of  rubber  tubing  to  the  glass 
tube  "I",  which  passes  through  the  small  furnace  "O"  which  is  main- 
tained at  a  temperature  of  150°  C.,  with  the  use  of  a  Bunsen  burner. 
This  tube  contains  iodine  pentoxide  which  oxidizes  the  carbon 
monoxide  to  carbon  dioxide,  the  latter  being  absorbed  in  a  .2  "N" 
solution  of  barium  hydroxide  contained  in  a  Meyer  tube  "B".  The 
iodine  which  is  formed  by  the  reaction  is  absorbed  by  the  barium 
hydroxide,  but  does  not  interfere  with  the  precipitation  of  barium 
carbonate.  The  iodine  acts  upon  the  rubber  tubing  making  it 
brittle,  this  action  can  be  lessened  by  passing  a  glass  rod  greased  with 
vaseline  through  the  new  rubber  tubing. 

After  heating  for  30  minutes  at  1000°  C.,  the  gas  is  turned  off 
and  the  air  blast  allowed  to  cool  the  silica  tube  "T",  for  ten  minutes. 
The  absorption  tube  is  detached  from  the  apparatus  and  is  con- 
nected with  the  aspirator  shown  in  engraving.  About  500  cc. 
of  air  purified  by  passing  through  stick  potash,  "K",  sulphuric  acid 
"S",  and  phosphoric  anhydride  "P"  respectively,  is  passed  through 
the  weighed  U  tube  "X".  This  is  done  for  the  purpose  of  displacing 
the  hydrogen  gas  and  prevents  errors  which  may  arise  should  the 
tubes  be  weighed  filled  with  hydrogen,  some  of  which  may  be  displaced 
by  air  should  the  stopper  become  dislodged.  Another  advantage 
is  that  the  U  tubes  are  quickly  cooled  by  aspirating  air  through  them, 
so  that  the  errors  from  weighing  tubes  at  different  temperatures  are 
eliminated. 

The  increased  weight  of  the  tube  "P",  due  to  the  water  which 
was  absorbed  is  multiplied  by  .8888,  divided  by  the  weight  taken  and 
multiplied  by  100,  which  gives  the  per  cent  of  oxygen. 

The  barium  carbonate  is  filtered  on  an  eleven  cm.  filter  paper, 
the  bulb  and  paper  being  washed  with  boiled  distilled  water  free 
from  carbon  dioxide.  The  filtering  should  be  done  at  a  location  where 
there  is  no  fuel  being  burned,  otherwise  some  carbonic  acid  gas  would 
be  absorbed.  The  filter  paper  containing  the  barium  carbonate  is 
ignited  first  at  low  temperature  and  finally  at  a  red  heat,  and  the 
white  barium  carbonate  weighed.  This  figure  is  multiplied  by 
.1418,  divided  by  the  weight  taken  and  multiplied  by  100  which  gives 
the  per  cent  of  carbon  monoxide  present. 


OXYGEN  157 

A  blank  determination  is  run  on  the  apparatus  each  day,  the 
apparatus  being  adjusted  until  the  final  blank  on  the  U  tube 
amounts  to  less  than  .003  grams.  The  final  figure  is  subtracted  from 
the  results  obtained  from  each  determination.  With  the  use  of 
electrolytic  hydrogen  there  will  be  no  blank  to  be  subtracted  from  the 
barium  carbonate. 

The  following  results  have  been  obtained  on  various  samples  of 
iron  and  steel: 

Material  Oxygen  Carbon  Monoxide 

Bureau  of  Standards,  No.  8a 064  .065 

Bureau  of  Standards,  No.  30 024  '.029 

American  Ingot  Iron 027  .013 

Basic  Open  Hearth  Steel 024  .073 

Puddled  Iron 572  .076 

Iron  Link  Newburyport  Bridge 027  .020 

-. 

J.  R.  Cain,  Bureau  of  Standards  Technologic  Paper  No.  118,  in 
studying  the  Ledebur  Method  for  determining  Oxygen  in  iron  and 
steel  has  developed  an  electrolytic  method  for  producing  pure  hy- 
drogen. The  following  ig  a  description  of  the  method: 

Electrolytic  Hydrogen  Generator  and  Reservoir 

Hydrogen  gas  was  generated  by  the  electrolysis  of  a  saturated 
solution  of  barium  hydroxide  mixed  with  a  25  per  cent  solution  of 
sodium  hydroxide  in  a  large  pyrex  glass  U  tube,  using  a  platinum 
anode  and  a  nickel  cathode.  Platinum  and  nickel  were  used  as  the 
electrode  materials  because  they  have  a  low  oxygen  and  a  low  hy- 
drogen overvoltage,  respectively. 

The  generator  (Page  160)  consists  of  a  U  tube  containing  the  elec- 
trolyte and  submerged  in  a  jar  through  which  flows  cold  water.  The 
bottom  of  the  U  is  filled  with  sea  sand  to  hinder  the  passage  of  dis- 
solved gas  from  one  limb  of  the  U  to  the  other,  as  suggested  by  Lewis, 
Brighton,  and  Sebastian.*  The  current  passing  through  the  genera- 
tor is  regulated  by  means  of  a  rheostat  in  the  circuit.  During  the 
course  of  the  investigation  the  current  used  by  the  operator  was  3.3 
amperes,  which  liberates  about  1.5  liters  of  hydrogen  gas  per  hour. 

The  hydrogen  gas  reservoir  and  pressure-maintaining  bottle  is 
connected  to  the  cathode  side  of  the  generator,  and  to  the  anode  side 
a  small  U  tube  of  10  mm.  inside  diameter  is  attached  which  con- 
tains mercury  to  balance  the  pressure  in  the  receiving  system.  With 
this  arrangement  the  generator  operates  automatically.  As  hydrogen 
is  generated  and  delivered  to  the  gas  reservoir  water  is  displaced  from 

*  J.  A.  C.  S.  39,   1917,  2248 


158 


OXYGEN 


Determination  of  Oxygen  in  Iron  and  Steel 

APPARATUS  FOR  DISPLACING  HYDROGEN  IN 
ABSORPTION  TUBE  WITH  DRY  AIR 

K — Tubes  containing  calcium  chloride. 
S — Tubes  containing  concentrated  sulphuric  acid. 
P — Tubes  containing  phosphoric  anhydride  on  glass  wool. 
X — Absorption  U  Tube,  used  for  weighing  the  moisture  obtained 
from  oxygen  in  the  sample. 


OXYGEN  159 

the  gas  reservoir  and  forced  into  the  water  bottle  above.  The  in- 
creased pressure  thus  produced  forces  down  the  liquid  in  the  cathode 
side  of  the  generator  an  amount  approximately  equal  to  the  height 
to  which  the  water  level  in  the  water  bottle  is  raised.  After  a  certain 
volume  of  hydrogen  gas  has  been  generated  and  stored  in  the  reser- 
voir, the  level  of  the  electrolyte  on  the  hydrogen  side  of  the  generator 
will  be  forced  down  out  of  contact  with  the  cathode,  thus  automat- 
ically breaking  the  circuit.  The  pressure  of  the  hydrogen  that  is  de- 
sired for  the  experiment  is  regulated  by  adjusting  the  height  of  the 
water  bottle,  which  then  determines  the  amount  of  mercury  that  must 
be  added  to  the  U  tube  on  the  oxygen  side  of  the  generator.  The 
hydrogen  gas  as  it  is  drawn  off  from  the  reservoir  for  use  is  passed 
through  the  catalyzer  and  purifying  train. 


160 


OXYGEN 


H,0  Wtt 


Electrolytic  hydrogen  venerator 


Electrolytic  hydrogen  generator 


PHOSPHORUS  161 


PHOSPHORUS 

DETERMINATION  OF  PHOSPHORUS 
ALKALI  TITRATION  METHOD 

Dissolve  2  grams  of  the  sample  in  40  cc.  of  nitric  acid,  1.18  specific 
gravity,  using  a  300  cc.  Erlenmeyer  flask.  Heat  on  hot  plate  until 
metal  is  in  solution  and  add  5  cc.  of  saturated  solution  permanganate 
of  potash. 

Boil  until  brown  precipitate  is  formed.  Now  add  four  cc.  of 
hydrochloric  acid,  1.20  specific  gravity  or  a  sufficient  amount  to  clear 
the  solution  by  boiling  a  few  minutes.  Avoid  an  excess  of  hy- 
drochloric acid  as  it  interferes,  with  the  precipitation  of  phosphorus 
when  extremely  low. 

Remove  from  hot  plate,  cool  somewhat,  and  cautiously  add 
ammonia,  .90  specific  gravity,  shaking  flask  occasionally,  until  a 
heavy  precipitate  of  ferric  hydroxide  is  formed.  Then  add  nitric 
acid,  1.42  specific  gravity,  shaking  occasionally,  until  precipitate 
dissolves  and  a  clear  amber-colored  solution  is  obtained. 

It  is  very  essential  that  an  excess  of  nitric  acid  should  be  avoided, 
as  it  interferes  with  the  precipitation  of  phosphorus  when  this  element 
exists  in  traces. 

Heat  or  cool  solution  to  85°  C.,  and  add  50  cc.  of  ammonium 
molybdate  solution.  Shake  well  and  allow  to  stand  at  least  J/£  hour 
or  until  precipitate  settles. 

Filter  and  wash  with  2%  nitric  acid  solution  until  free  from  iron, 
and  finally  with  distilled  water  containing  about  1  gram  of  potassium 
nitrate  to  liter  until  free  from  acid. 

Transfer  filter  and  contents  to  tumbler  containing  50  cc.  of  boiled 
distilled  water.  Disintegrate  paper  writh  two  stirring  rods  and  add 
sufficient  standard  sodium  hydroxide  to  dissolve  the  yellow  precipitate 
and  render  the  solution  pink  when  phenolphtalein  indicator  is  added. 
Now  run  in  standard  nitric  acid  until  pink  color  disappears,  then  finish 
the  titration  with  standard  alkali,  the  end  point  being  a  faint  pink  color. 
TITRATIOX  EXAMPLE 

Standard  Alkali  Standard  Acid 

Last  Reading 27 .5  cc.  Last  Reading 14.7  cc. 

First  Reading 17 .3  First  Reading 6.7 

10.2cc.  S.Occ. 

2.2  cc.  x  .01  =  .022%  Phos. 


Ib2  PHOSPHORUS 

Standard  Solutions 

The  standard  nitric  acid  and  alkali  used  for  titrating  are  about 
.15  normal.  One  cc.  being  equal  to  .01%  Phosphorus  when  a  2-gram 
sample  is  used  for  analysis. 

A  stock  solution  of  sodium  hydroxide  is  prepared  by  dissolving 
192  grams  of  sodium  hydroxide  in  water  and  adding  enough  barium 
hydroxide  solution  to  precipitate  all  carbonates,  then  diluting  to  two 
liters.  Use  50  cc.  of  stock  solution  diluted  to  two  liters  for  the 
standard  alkali  solution. 

A  stock  solution  of  nitric  acid  for  titrating  can  be  prepared  by 
mixing  367  cc.  of  concentrated  nitric  acid,  specific  gravity  1.42,  with 
enough  boiled  distilled  water  free  from  carbon  dioxide  to  make  two 
liters.  Use  50  cc.  stock  solution  diluted  to  two  liters  for  the  standard 
acid  solution. 

Nitric  Acid  for  dissolving  the  sample  can  be  prepared  by  adding 
1  part  of  nitric  acid,  1.42  specific  gravity,  to  2  parts  of  water.  The 
specific  gravity  of  this  mixture  will  be  very  close  to  1.18. 

Ammonium  Molybdate  Solution 

Preparation 

Place  in  5-pint  bottle: 

500  cc.  Cone.  HNO3,  Sp.  Gr.  1.42. 
1700  cc.  Distilled  Water. 
Place  in  400  cc.  beaker: 

90  g.  Molybdic  Acid. 
100  cc.  Distilled  Water. 
100  cc.  Cone.  Ammonia. 

Add  ammonium  molybdate  slowly  to  acid  in  bottle  while  stirring. 
Mix  thoroughly  then  add  2  drops  only  saturated  ammonium  phosphate 
solution.  Agitate  and  let  settle. 

Use  40  cc.  to  50  cc.  of  clear  solution. 


PHOSPHORUS  163 

MODIFICATION  FOR  DETERMINING  PHOSPHORUS 
IN  CHROME-VANADIUM  STEEL 

On  account  of  the  vanadium  interfering  with  the  determination 
of  phosphorus  we  use  the  method  of  Hagmaier,  described  in  Metal- 
lurgical and  Chemical  Engineering,  Vol.  XI,  p.  28.  This  method  is 
about  as  follows: 

Dissolve  2  g.  of  the  steel  in  aqua  regia  in  a  4-in.  casserole, 
evaporate  to  dryness  and  bake.  Cool,  dissolve  in  35  cc.  of  concentrated 
hydrochloric  acid,  dilute  with  water  and  filter  from  silica. 

Reduce  the  filtrate  with  sulphurous  acid.  When  entirely  reduced 
add  5  cc.  of  90%  acetic  acid  and  10  cc.  of  a  saturated  solution  of 
cerium  chloride.  Add  dilute  ammonia  with  constant  stirring  until 
the  solution  becomes  turbid.  Then  heat  the  solution  to  boiling, 
allow  to  settle,  and  filter.  The  cerium  phosphate  will  filter  rapidly. 
Wash  the  precipitate  several  times  with  hot  wrater  and  then  dissolve 
off  the  paper  with  hot  1 :1  nitric  acid. 

Precipitate  the  phosphorus  from  this  solution  in  the  regular 
manner  with  ammonium  molybdate  and  titrate  with  alkali  as  previ- 
ously described.  Add  ammonia  very  slowly,  as  it  is  impossible  to 
obtain  proper  conditions  if  an  excess  is  added  and  an  attempt  is  made 
to  neutralize  with  acid.  Should  an  excess  inadvertently  be  added  it 
is  best  to  start  another  determination  instead  of  attempting  to  neu- 
tralize the  excess  of  ammonia. 


164 


PHOSPHORUS 


<u    rt 

•X     g 

.s  §> 

i! 


O      QJ 


I 

O 

CJ 

'§ 

CQ 


PIN  HOLE  TEST  165 


PIN  HOLE  TEST 
LEAD  COATED,  TIN  AND  TERNE  PLATE 

Dr.  Allerton  S.  Cushman  has  devised  a  very  simple  test  to  de- 
termine the  number  of  pin  holes  per  square  foot.  The  test  consists 
of  exposing  a  full  sized  sheet  to  the  action  of  distilled  water.  The 
pin  holes  appear  as  rust  spots. 

The  four  sides  of  the  sheet  are  bent  so  as  to  make  a  pan  1"  deep. 
The  pan  is  thoroughly  cleaned  with  several  applications  of  gasoline 
and  then  flooded  to  a  depth  of  Y^'  with  distilled  water.  After  one 
week's  exposure  the  water  is  removed  and  the  pin  holes  are  counted. 


166 


PIN  HOLE  TEST 


-o 

<u  .£;  a; 

SIS 

Xi  6  «J 

111 

—  ^  aj 


s  s  ° 

o'S  52 
•*  §  £§ 
_£  <y  b-S 

•5^35 
13  £  gr 

^^53 


^  o 

J'i1 

tn   o_ 

<   ^3 


D 

1 


O    <U  JC 

H-5.a 

-1 


SILICON  167 


SILICON 

THE  DETERMINATION  OF  SILICON  IN 
IRON  AND  STEEL 

Dissolve  4.69  grams  of  the  sample  in  a  platinum  dish,  using  60 
cc.  of  nitric  acid,  1.18  specific  gravity,  and  10  cc.  of  sulphuric  acid, 
1.84  specific  gravity.  Evaporate  to  dense  white  fumes  and  when 
cool  dissolve  ferric  sulphate  in  about  35  cc.  of  hydrochloric  acid,  1.20 
specific  gravity.  Dilute  with  water  and  filter  through  an  ashless 
paper.  Wash  alternately  with  distilled  water  and  dilute  hydrochloric 
acid,  1.05  specific  gravity,  until  free  from  iron. 

Ignite  in  platinum  crucible,  using  a  muffle  for  this  purpose.  If 
muffle  is  not  available  use  a  Meker  burner  w^ith  natural  draft. 

Weigh  residue  and  add  about  1  cc.  of  hydrofluoric  acid  and  about  3 
drops  of  concentrated  sulphuric  acid.  Heat  crucible  carefully  from 
the  top  of  the  crucible  instead  of  from  the  bottom,  and  when  all  acid 
has  evaporated  heat  to  the  full  temperature  of  burner  until  iron  has 
changed  to  oxide.  Cool  and  weigh.  The  loss  is  silica.  Each 
milligram  equals  .01%  of  silicon. 

Notes  on  Method 

If  silicon  is  determined  in  alloys  containing  chromium,  the 
evaporation  of  the  acids  should  not  be  done  at  high  temperatures. 
This  evaporation  should  be  conducted  on  hot  plate,  as  some  chromic 
oxide  is  liable  to  separate. 

If  the  silica  after  ignition  is  canary  yellow  in  color,  it  indicates 
the  presence  of  tungsten.  The  residue  remaining  in  the  crucible 
after  treatment  with  hydrofluoric  acid  will  consist  essentially  of 
tungsten  trioxide  (WOs).  For  accurate  results,  however,  the  regular 
method  should  be  employed  for  the  determination  of  this  element. 

If  silicon  is  to  be  determined  in  Pig  Iron,  use  2.35  grams.  Dis- 
solve in  a  porcelain  dish  instead  of  a  platinum  dish,  using  50  cc.  of  the 
following  mixture: 

Water 68% 

Cone.  Nitric  Acid 23)4% 

Cone.  Sulphuric  Acid 


168  SILICON 

If  silicon  is  being  determined  in  alloy  steels,  omit  the  use  of 
platinum  dish  and  use  the  following  mixture  of  acids  which  will  pre- 
vent bumping  or  spattering: 

Water 55% 

Cone.  Nitric  Acid 25% 

Cone.  Sulphuric  Acid 10% 

Cone.  Hydrochloric  Acid 10% 

Note — In  the  case  of  Pure  Iron  and  Steel  which  contains  a  trace  of 
silicon  we  use  4.59  grams  of  the  sample,  using  nitric  and  sulphuric 
acid  in  a  platinum  dish. 

For  steel  containing  appreciable  amounts  of  silicon  we  use 
2.35  grams  of  the  sample  and  50  cc.  of  the  above  acid  mixture  in  a 
porcelain  dish. 


SILICON,  ALUMINUM,  TITANIUM  AND   ZIRCONIUM  169 

THE  DETERMINATION  OF  SILICON,  ALUMINUM, 
TITANIUM  AND  ZIRCONIUM  IN  STEEL 


BUREAU  OF  STANDARDS 


Dissolve  5.00  grams  of  the  steel  in  50  cc.  of  hydrochloric  acid 
(sp.  gr.  1.2)  by  gentle  warming  and  the  addition  of  1  cc.  portions  of 
nitric  acid  from  time  to  time  to  insure  solution  of  the  zirconium  and 
titanium  and  also  oxidation  of  the  iron. 

When  solution  is  complete,  evaporate  to  dryness,  take  up  in 
10  cc.  of  hydrochloric  acid  (sp.  gr.  1.2),  again  evaporate  to  dryness, 
and  finally  bake  at  a  gentle  heat  in  order  to  decompose  nitrates. 

Cool,  take  up  in  50  cc.  of  1:1  hydrochloric  acid,  and  filter  when 
the  iron  is  completely  in  solution.  Wash  the  residue  with  cold  1:1 
hydrochloric  acid.  Save  the  filtrate  and  washings. 

Ignite  the  residue  and  paper  in  a  platinum  crucible,  cool  and  weigh. 
Treat  with  1  cc.  of  sulphuric  acid  (1:1)  and  sufficient  hydrofluoric 
acid,  fume  off  in  the  usual  manner,  ignite  and  weigh  to  obtain  silica, 
and  calculate  silicon. 

Fuse  the  slight  residue  left  after  the  hydrofluoric  acid  treatment 
with  a  small  amount  of  potassium  pyrosulphate,  dissolve  in  10-20 
cc.  of  5%  sulphuric  acid  and  add  the  solution  to  the  acid  extract  from 
the  ether  separation  obtained  as  described  below. 

Evaporate  the  filtrate  and  washings  from  the  silica  determination 
to  a  syrupy  consistency,  take  up  in  40  cc.  of  hydrochloric  acid  (sp. 
gr.  1.1)  and  extract  with  ether  in  the  usual  manner.  (The  ether 
extract  will  contain  most  of  the  molybdenum,  and  this  element  may 
be  qualitatively  tested  for  in  it.  If  molybdenum  is  present  it  is  more 
conveniently  determined  in  a  separate  portion  of  steel).  The  acid 
extract  will  contain  some  iron,  and  all  of  the  zirconium,  titanium, 
aluminum,  nickel,  chromium,  etc. 

Gently  boil  off  the  ether  in  the  acid  extract,  add  the  matter 
recovered  from  the  s'lica,  oxidize  ferrous  iron  with  a  little  nitric  acid, 
dilute  to  300  cc,  cool  and  precipitate  with  20%  sodium  hydroxide 
solution,  adding  10  cc.  in  excess.  Filter,  and  save  the  filtrate.  Dis- 
solve the  precipitate  in  warm  dilute  1 :1  hydrochloric  acid  and  repeat 
the  precipitation.  Combine  the  sodium  hydroxide  filtrates.  Dis- 
solve the  precipitate  as  above  and  reserve  the  solution  for  subsequent 
analvsis. 


170  SILICON,  ALUMINUM,  TITANIUM  AND    ZIRCONIUM 

It  is  advisable  to  treat  as  follows  the  filter  or  filters  used  above: 
Ignite  in  platinum,  fuse  with  sodium  carbonate,  digest  the  cooled 
melt  with  hot  water,  wash  the  residue,  discard  the  filtrate  and 
washings,  dissolve  the  residue  in  hot  1  :1  hydrochloric  acid  and  add  to 
the  main  acid  solution.  This  precaution  makes  certain  the  recovery 
of  any  zirconium  held  back  on  the  filter  as  zirconium  phosphate  in- 
soluble in  acid. 


Five  samples  of  pig  iron  are  taken  from  each  carload  received.     Samples  are  broken 
with  a  sledge  and  taken  to  the  chemical  laboratory  for  analysis 


SILICON,  ALUMINUM,  TITANIUM  AND  ZIRCONIUM  171 

DETERMINATION  OF  ALUMINUM  IN  THE  ABSENCE 
OF  CHROMIUM 

Add  a  few  drops  of  methyl  red  to  the  sodium  hydroxide,  filtrate, 
neutralize  with  hydrochloric  acid,  add  4  cc.  of  concentrated  hy- 
drochloric acid  per  100  cc.  of  solution,  boil,  make  barely  alkaline  with 
ammonium  hydroxide,  continue  the  boiling  for  three  minutes  and  then 
set  the  beaker  aside  for  ten  minutes.  If  no  precipitate  settles  out, 
the  absence  of  aluminum  is  assured.  If  a  white  precipitate  settles 
out,  aluminum  is  indicated;  this  precipitate  is  always  contaminated 
by  phosphorus  pentoxide  and  must  be  purified  as  follows :  filter  with- 
out washing,  discard  the  filtrate  and  dissolve  the  precipitate  in  warm 
1:1  hydrochloric  acid.  Dilute  the  solution  to  50  cc.,  make  alkaline 
with  ammonium  hydroxide,  neutralize  with  nitric  acid  and  add  2  cc. 
in  excess.  Warm  to  50°  C.,  precipitate  the  phosphoric  acid  with 
molybdate  reagent  in  the  usual  manner,  filter,  and  wash  the  phospho- 
molybdate  with  ammonium  acid  sulphate  solution.  Precipitate  the 
aluminum  in  the  filtrate  as  directed  above,  filter  without  washing, 
dissolve  the  precipitate  in  warm  1:1  hydrochloric  acid,  reprecipitate, 
filter,  wash  slightly  with  2%  ammonium  chloride  solution  and  ignite 
in  a  platinum  crucible.  The  ignited  residue  is  usually  contaminated 
by  silica,  therefore  a  sulphuric  acid-hydrofluoric  acid  treatment 
followed  by  ignition  over  the  blast  lamp  to  alumina  should  be  per- 
formed. (The  sodium  hydroxide  reagent  must  be  tested  for  sub- 
stances which  are  precipitated  by  ammonia,  and  appropriate  corrections 
must  be  made  in  the  aluminum  determination  when  these  are  present). 


SILICON,  ALUMINUM,  TITANIUM  AND  ZIRCONIUM 


SILICON,  ALUMINUM,  TITANIUM  AND   ZIRCONIUM  173 


DETERMINATION  OF  ALUMINUM  IN  STEELS 
CONTAINING  CHROMIUM 

Proceed  as  above  until  the  nitrate  from  the  molybdate  precipi- 
tation is  obtained.  Then  make  the  solution  ammoniacal,  oxidize 
with  a  little  bromine  water,  make  just  acid  with  1 :2  nitric  acid,  add 
ammonium  hydroxide  in  slight  excess,  heat  to  boiling,  filter,  dissolve 
the  precipitate  in  dilute  hydrochloric  acid,  and  reprecipitate  the 
aluminum  hydroxide  as  directed  above. 


DETERMINATION  OF  ALUMINUM  IN  STEELS 
CONTAINING  URANIUM 

The  only  modification  which  is  required  is  the  substitution  of 
ammonium  carbonate  for  ammonium  hydroxide  as  the  final  precipi- 
tant of  the  aluminum  hydroxide. 


DETERMINATION  OF  ALUMINUM  IN  STEELS 
CONTAINING  VANADIUM 

Alumina  which  is  obtained  by  the  above  procedures,  from  steels 
containing  vanadium,  is  contaminated  by  this  element.  When 
dealing  with  these  steels  proceed  as  follows :  fuse  the  weighed  residue 
with  pyrosulphate,  extract  the  cooled  melt  with  5%  sulphuric  acid, 
reduce  the  vanadium  in  a  Jones  reductor  having  ferric  alum  in  the 
receiver,  titrate  the  reduced  solution  with  standard  permanganate, 
calculate  the  vanadium  as  V2O5  and  subtract  from  the  original 
weight. 


174 


SILICON,  ALUMINUM,  TITANIUM  AND  ZIRCONIUM 


Ill 

•~^^ 

2  aS 
I-"l 
3|§ 


CN       QJ       " 

§a* 

G  <u.ti 

CSVj'S 


M.,   tn   rt 

-M    OJ 

IP 

o.S  ^ 

»gl 

.s  M1B 

OJ    0)    o 

-^-^  J5 

en  "*"*  'p, 

ill 

X    «*» 

*°2 

c  S  as 

2  o;^ 
'S^g, 

^  8.S 

o'So 
S^ 

-^ 


o  jn 


SILICON,  ALUMINUM,  TITANIUM  AND  ZIRCONIUM  175 

DETERMINATION  OF  ZIRCONIUM  AND  TITANIUM 

Dilute  the  hydrochloric  acid  solution  to  250  cc.,  neutralize  with 
ammonium  hydroxide  so  as  to  leave  approximately  5%  (by  volume) 
of  hydrochloric  acid,  add  2  grams  of  tartaric  acid,  and  treat  with 
hydrogen  sulphide  until  the  iron  has  been  reduced.  Filter  if  the 
sulphide  group  is  indicated.  Make  the  hydrogen  sulphide  solution 
ammoniacal  and  continue  the  addition  of  the  gas  for  5  minutes. 
Filter  carefully  and  wash  with  dilute  ammonium  sulphide-ammonium 
chloride  solution.  Filter  through  a  new  filter  if  the  presence  of  iron 
sulphide  in  the  filtrate  is  indicated.  Save  the  filtrate. 

(The  sulphide  precipitate  consists  of  ferrous  sulphide,  in  addition 
to  the  greater  part  of  any  nickel,  cobalt  and  manganese  present  in 
steel.  It  is  preferable  to  determine  these  in  separate  portions  of  the 

steel) . 

Neutralize  the  ammonium  sulphide  filtrate  with  sulphuric  acid, 
add  30  cc.  in  excess  and  dilute  with  water  to  300  cc.  Digest  on  the 
steam  bath  until  sulphur  and  sulphides  have  coagulated,  filter,  wash 
with  100  cc.  of  10%  sulphuric  acid  and  cool  the  filtrate  in  ice  water. 

Add  slowly  and  with  stirring  an  excess  of  a  cold  6%  water  solu- 
tion of  cupferron.  (The  presence  of  an  excess  is  shown  by  the  ap- 
pearance of  a  white  cloud  which  disappears,  instead  of  a  permanent 
coagulated  precipitate).  Immediately  filter  on  paper,  using  a  cone 
and  very  gentle  suction,  and  wash  thoroughly  with  cold  10%  hydro- 
chloric acid. 

Carefully  ignite  in  a  tared  platinum  crucible,  completing  the 
ignition  over  a  blast  lamp  or  large  Meker,  cool  and  weigh  the  com- 
bined zirconium  and  titanium  oxides. 

Fuse  with  potassium  pyrosulphate,  dissolve  in  50  cc.  of  10% 
(by  volume)  sulphuric  acid  and  determine  titanium  colorimetrically 
or  volumetrically.  Calculate  titanium  oxide  and  subtract  the 
weight  found  from  that  of  the  combined  oxides  and  calculate  zir- 
conium. 

Notes: 

1.  Phosphorus    pentoxide   contaminates   the    precipitate    to   so 
slight  an  extent  that  it  can  be  disregarded. 

2.  Vanadium  interferes  no  matter  what  its  valency.     The  in- 
terference is  not  quantitative.       If  present  in  the  steel,  proceed  as 
usual  through  the  weighing  of  the  cupferron  precipitate.       Then  fuse 
thoroughly  with  sodium  carbonate,  cool,  extract  with  water,  filter, 


176  SILICON,  ALUMINUM,  TITANIUM  AND   ZIRCONIUM 

and  determine  the  vanadium  in  the  filtrate  by  adding  sulphuric  acid, 
reducing  through  a  Jones'  reductor  into  a  solution  of  ferric  phosphate 
and  then  titrating  with  standard  permanganate.  Ignite  in  the 
original  crucible  the  matter  insoluble  in  water,  fuse  with  potassium 
pyrosulphate  and  proceed  as  directed  for  titanium. 

3.  Tungsten  does  not  interfere   since  it  is  separated  from  zir- 
conium and  titanium  by  the  sodium  hydroxide  treatment,  and  from 
aluminum  by  the  ammonium  hydroxide  precipitation.       If  tungsten 
is  present  in  large  amount  it  may  be  found  desirable  to  fuse  the  non- 
volatile residue  from  the  silicon  determination  with  sodium  carbonate, 
extract  with  water,  filter,  dissolve  the  residue  in  hot  1 :1  hydrochloric 
acid  and  add  to  the  acid  extract  from  the  ether  separation. 

4.  Uranium    is    partially    carried    down    when    present    in    the 
tetravalent  condition,  but  at  not  all  in  the  hexavalent  state.     If  this  ele- 
ment is  suspected,   boil  out  all  hydrogen  sulphide  before  the  cup- 
ferron  precipitation,  oxidize  with  permanganate  to  a  faint  pink,  cool 
and  proceed  with  the  cupferron  precipitation. 

5.  Thorium   and   cerium   interfere,    but   they   are    not   thrown 
down   quantitatively.        In   case   these  elements   are  suspected,   the 
peroxidized  solution   used  for  the  titanium  determination  must  be 
quantitatively  preserved   and   reduced  with   a  little  sulphuric  acid. 
The  rare  earths  are  then  separated  by  Hillebrand's  method1  as  follows: 
precipitate  the  hydroxides  with  an  excess  of  potassium  hydroxide, 
decant  the  liquid,  wash  by  decantation  with  water  once  or  twice  and 
then  slightly  on  the  filter.      Wash  the  precipitate  from  the  paper  into 
a  small  platinum  dish,  treat  with  hydrofluoric  acid,  and  evaporate 
nearly  to  dryness.      Take  up  in  5  cc.  of  5%  (by  volume)  hydrofluoric 
acid.        If  no  precipitate  is  visible,   rare  earths  are  absent.       If  a 
precipitate  is  present,  collect  it  on  a  small  filter  held  by  a  perforated 
platinum  or  rubber  cone  and  wash  it  with  from  5  to  10  cc.  of  the  same 
acid.       Wash  the  crude  rare-earth  fluorides  into  a  small  platinum 
dish,  burn  the  paper  in  platinum,  add  the  ash  to  the  fluorides  and 
evaporate   to   dryness  with   a   little   sulphuric   acid.        Dissolve   the 
sulphates    in    dilute    hydrochloric    acid,    precipitate    the    rare-earth 
hydroxides  by  ammonia,  filter,  redissolve  in  hydrochloric  acid,  evapor- 
ate the  solution  to  dryness,  and  treat  the  residue  with  5  cc.  of  boiling 
hot  5%  oxalic  acid.      Filter  after  fifteen  minutes,  collect  the  oxalates 
on  a  small  filter,  wash  with  not  more  than  20  cc.  of  cold  5%  oxalic 
acid,  ignite  and  weigh  as  rare-earth  oxides  which  are  to  be  deducted 
from  the  weight  of  the  cupferron  precipitate. 

1  U.  S.  Geol.  Survey  Bulletin  700,  The  Analysis  of  Silicate  and  Carbonate  Rocks,  p.  176. 


SILICON,  ALUMINUM,  TITANIUM  AND   ZIRCONIUM  177 

The  foregoing  procedure  does  not  give  an  absolutely  quantitative 
recovery  of  the  rare  earths.  Experiments  indicate  a  recovery  of 
approximately  85%  of  the  rare  earths  present  in  residues  containing 
100  mg.  of  zirconia,  2  mg.  of  thoria  and  2  mg.  of  ceria. 

Attempts  which  were  made  to  omit  the  preliminary  separation 
of  the  rare  earths  as  fluorides  were  unsuccessful. 

6.  Instead  of  the  prescribed  treatment  for  the  removal  of  the 
bulk  of  the  iron,  Johnson's2  method  of  fractional  ammonium  hy- 
droxide precipitation  may  be  used.  When  using  this  method,  it  is 
recommended  that  the  1:1  hydrochloric  acid  solution  of  the  ammo- 
nium hydroxide  precipitate  should  be  further  treated  as  given  in  the 

Bureau    of   Standards   method  beginning  with  "oxidize and 

precipitate  with  a  20%  sodium  hydroxide  solution".       In  Johnson's 
procedure  silicon  must  be  determined  in  a  separate  portion. 

2  C.  M.  Johnson,  Chem.  and  Met.  Eng.  20,  1919,  p.  588. 


178 


SILICON,  ALUMINUM,  TITANIUM  AND  ZIRCONIUM 


§1 


J.s 


si 


"3 


a 


5-5 


il 

c  •*-" 

<U   w 

O    05 


SPELTER  COATING  179 

CUSHMAN'S  METHOD  FOR  THE 

DETERMINATION  OF  SPELTER  COATING  BY 

MEASURING  THE  HYDROGEN  EVOLVED1 

The  determination  of  the  weight  of  spelter  coating  by  this  method 
is  based  upon  the  action  of  hydrochloric  acid  upon  the  galvanized 
coating,  collecting  and  measuring  the  hydrogen  gas  evolved2.  The 
weight  of  coating  may  be  determined  upon  flat  sheets,  corrugated 
sheets,  and  formed  culverts,  by  the  use  of  differently  shaped  rings 
provided  with  the  apparatus.  The  coating  upon  wire  can  be  de- 
termined by  placing  a  definite  length  of  wire  under  the  flat  ring  on 
a  glass  plate. 

The  metallic  rings  are  made  of  nickel,  tinned  iron,  or  other  acid 
resisting  metal,  and  are  fitted  with  No.  12,  three-hole  rubber  stoppers. 
Through  one  hole  passes  the  filling  tube  provided  with  glass  stopcock. 
Through  the  other  holes  pass  the  exit  tubes,  the  short  tube  to  a  posi- 
tion even  with  the  bottom  of  the  stopper,  the  long  tube  extending  to  a 
position  even  with  the  bottom  of  the  ring.  A  measuring  burette  and 
leveling  bottle  are  provided  for  collecting  and  measuring  the  hydrogen 
evolved. 

The  measuring  burette  is  first  filled  with  water,  allowing  a  small 
amount  of  water  in  the  leveling  bottle.  The  proper  ring  is  selected 
for  the  culvert  to  be  tested,  and  is  placed  upon  the  culvert  and  sealed 
with  "Plasteline",  or  other  acid  resisting  wax.  The  stopcock  on  the 
acid  tube  is  turned  so  as  to  communicate  with  the  short  tube,  and  is 
then  connected  with  the  measuring  burette  by  means  of  a  rubber 
tube.  Water  is  now  placed  in  the  filling  tube,  the  stopcock  opened, 
and  the  ring  and  connecting  tubes  completely  filled  with  water  by 
lowering  the  leveling  bottle,  and  allowing  the  air  to  flow  into  the 
burette.  By  means  of  the  three  way  stopcock  on  the  measuring 
burette,  it  is  again  filled  with  water  without  disturbing  the  water  in 
the  ring. 

The  stopcocks  in  the  measuring  burette  are  opened  and  the 
stopcock  on  the  exit  tube  turned  to  connect  the  long  tube  with  the 
burette.  If  there  are  any  leaks  in  the  apparatus  the  water  in  the 
measuring  burette  will  fall.  With  everything  prepared  and  ready, 
about  30  cc.  of  concentrated  hydrochloric  acid  are  placed  in  the  filling 
tube  and  about  5  cc.  admitted  to  the  ring.  The  hydrogen  generated 
from  the  zinc  will  force  out  the  wrater  in  the  ring.  As  soon  as  gas 
appears  in  the  long  exit  tube,  the  stopcock  is  quickly  reversed  to  the 

1  Dr.  A.  S.  Cushman,  Proceedings  of  The  American  Society  for  Testing  Materials,  1920. 

2  The  apparatus  for    making  this    test  can  be   obtained    from    the    Kauff man  -  Lattimer    Co., 
Columbus,  Ohio. 


180 


SPELTER  COATING 


ho 

.s 

cti 

6 


X 

'o 

£ 

C£ 

1 

<u 


SPELTER  COATING  181 

short  exit  tube,  3  cc.  of  antimony  chloride  solution2  are  added  to  the 
acid  in  the  filling  tube  and  the  acid  allowed  to  run  into  the  ring. 

When  the  generation  of  gas  has  ceased,  the  ring  and  connecting 
tube  are  completely  filled  with  water  through  the  filling  tube  by  lower- 
ing the  leveling  bottle,  and  as  soon  as  the  liquid  reaches  the  burette 
the  stopcock  is  turned  off,  the  water  in  the  leveling  bottle  and  burette 
brought  to  the  same  level  and  the  volume  of  hydrogen  recorded. 

The  burette  stopcock  is  now  turned  to  communicate  with  the 
waste  beaker  and  enough  water  passed  through  the  ring  by  means 
of  the  filling  tube  to  remove  all  acid.  By  turning  the  stopcock  to 
the  long  exit  tube  the  ring  can  be  completely  drained.  In  case  the 
ring  is  lower  than  the  burette  stopcock  it  is  necessary  to  blow  out  the 
water  with  a  rubber  tube  and  stopper  inserted  in  the  filling  tube. 
The  ring  can  then  be  removed  and  the  spot  on  the  culvert  cleaned 
with  gasoline.  The  spot  may  then  be  coated  writh  a  paste  of  zinc 
powder  and  zinc  chloride  (50%  solution)  and  heated  with  a  blowtorch 
until  fused,  or  it  may  be  coated  with  a  zinc  powder  paint  or  aluminum 
paint. 

The  number  of  cubic  centimeters  of  hydrogen  measured  at  20°  C. 
(75°  F.)  multiplied  by  the  factor  provided  with  each  ring  will  give  the 
ounces  of  spelter  coating  per  square  foot  of  actual  surface  on  one  side 
of  the  culvert.  By  doubling  this  figure  the  coating  in  ounces  per 
square  foot  of  sheet  surface  can  be  obtained.  The  factors  for  each 
ring  are  given  in  a  table  accompanying  the  apparatus. 

2  Five  grams  of  antimony  chloride  dissolved  in  100  cc.  of  concentrated  hydrochloric  acid,  Sp. 
Gr.  1.20. 


182 


SPELTER  COATING 


SPELTER  COATING  183 

THE  DETERMINATION  OF  SPELTER^COATING 
ON  SHEETS  AND  WIRE 

HYDROCHLORIC  ACID  METHOD 

For  many  years  the  Preece  copper-sulfate  test  has  been  used  to 
determine  the  amount  of  galvanized  coating  on  sheets  and  wire. 
Committee  A-5  on  the  Corrosion  of  Iron  and  Steel,  The  American 
Society  for  Testing  Materials,  reported  to  the  Society  in  1911  on  this 
test  as*  follows: 

"It  is,  however,  the  unanimous  opinion  of  the  committee  that 
the  well-known  Preece  copper-sulfate  test  is  unreliable  and  should 
be  abandoned  entirely  as  a  basis  of  specification  with  respect  to  gal- 
vanized sheet  and  plate.  In  respect  to  wrire,  the  Preece  test  has  the 
advantage  of  being  quick  and  simple,  and  if  carried  out  in  the  proper 
manner,  yields  comparative  results  of  value.  In  the  opinion  of  the 
committee,  the  lead-acetate  is  preferable  to  the  copper-sulfate  test 
for  determining  or  specifying  the  weight  of  zinc  coatings.'.' 

The  lead-acetate  method  recommended  by  Committee  A-5  in  1911 
yields  very  accurate  and  satisfactory  results,  but  the  length  of  time 
required  for  making  the  test  seriously  limits  the  scope  of  its  usefulness. 
The  results  obtained  with  the  method  described  in  this  paper  compare 
very  favorably  with  those  of  the  lead-acetate  method. 

There  is  much  to  be  desired  in  the  method  of  expressing  the 
weight  of  coating  on  wire  products  in  order  to  have  an  intelligent 
understanding  as  to  the  weight  of  coating  per  unit  area.  It  has  been 
customary  to  express  the  weight  of  coating  on  wire  in  pounds  per  mile, 
while  on  sheet  products  the  results  are  usually  expressed  in  ounces 
per  square  foot.  Obviously,  the  coating  on  wire  expressed  in  pounds 
per  mile  would  have  a  different  meaning  for  each  gage  of  wire.  If  the 
results  are  expressed  in  ounces  per  square  foot  of  surface  on  both  wire 
and  sheets,  there  wrill  be  a  better  understanding  as  to  the  thickness  of 
coating  on  the  respective  products.  In  stating  the  weight  of  coating 
on  galvanized  sheets  it  is  customary  to  express  the  weight  based  on  one 
surface  only,  that  is,  a  sheet  containing  2  oz.  of  coating  per  square 
foot  really  contains  1  oz.  on  each  side  of  the  sheet. 

It  is  proposed  to  express  the  weight  of  coating  on  wire  in  ounces 
per  square  foot,  and  also  to  use  such  lengths  of  wire  that  the  number 
of  grams  of  coating  found  wrill  be  equivalent  to  ounces  per  square  foot, 


184  SPELTER  COATING 

without  calculation.  These  lengths  must  be  such  that  the  surface 
coated  is  equal  to  5.079  sq.  in.  It  is  likewise  proposed  that  the 
samples  for  determining  the  weight  of  coating  on  galvanized  sheets 
shall  be  234  by  2/4  in.  (area  =  5.079  sq.  in.).  The  number  of  grams 
of  coating  on  a  section  of  this  size  will  also  express  the  weight  of 
coating  in  ounces  per  square  foot  without  calculation. 

The  method  for  determining  the  weight  of  spelter  coating  con- 
sists of  using  a  small  amount  of  antimony  chloride  in  hydrochloric 
acid  (sp.  gr.  1.20).  Antimony  chloride  appears  to  hasten  the  solution 
of  the  coating,  and  after  the  coating  has  dissolved  a  thin  film  of  anti- 
mony plates  on  the  surface  of  the  base  metal  and  retards  the  solution 
of  iron  or  steel.  Experiments  have  shown  that  sheet  steel  2J4  by 
2/4  in.  which  loses  50  mg.  in  five  minutes  in  cold  hydrochloric  acid 
(sp.  gr.  1.20),  will  lose  in  that  time  only  1  mg.  in  the  same  acid  con- 
taining 80  mg.  of  antimony  per  105  cc.  of  acid. 

In  the  proposed  method  the  metal  is  immersed  in  the  acid  only 
one  minute,  which  is  long  enough  to  dissolve  several  grams  of  coating, 
yet  the  amount  of  iron  or  steel  dissolved  is  negligible.  The  small 
amount  of  antimony  that  plates  on  the  surface  of  the  sample  can 
easily  be  removed  by  scrubbing  under  running  water.  This  method 
is  one  of  the  most  rapid  and  accurate  with  which  the  writer  is  familiar, 
and  a  determination  can  be  made  in  less  time  than  is  occupied  in 
making  the  Preece  test. 

SHEETS — For  determining  the  weight  of  coating  on  galvanized 
sheets,  cut  three  samples  2^4  by  2M  in.  from  a  strip  cut  from  middle 
of  sheet  as  shown  on  Page  186.  The  three  samples  should 
be  weighed  together  and  immersed  singly  for  one  minute  in 
100  cc.  of  hydrochloric  acid  (sp.  gr.  1.20),  to  which  has  been  added  5 
cc.  of  antimony  chloride  prepared  by  dissolving  20  g.  of  antimony 
trioxide  in  1000  cc.  of  hydrochloric  acid  (sp.  gr.  1.20).  The  same 
100  cc.  of  hydrochloric  acid  can  be  used  for  at  least  five  samples. 
Five  cubic  centimeters  of  the  antimony  chloride,  however,  should  be 
added  for  each  sample  on  account  of  the  antimony  being  removed 
from  the  solution  by  the  iron. 


SPELTER  COATING  185 

The  samples  are  washed  and  scrubbed  under  running  water, 
dried  with  a  towel,  and  laid  in  a  warm  place  for  a  few  seconds.  The 
samples  are  again  weighed  together  and  the  number  of  grams  lost  is 
divided  by  the  number  of  samples  taken.  Each  gram  corresponds 
to  1  oz.  of  coating  per  square  foot. 

Wire— A  small  section  of  the  galvanized  wire  should  be  stripped 
in  hydrochloric  acid  containing  antimony  chloride.  The  diameter 
of  the  black  wire  should  then  be  carefully  measured  in  order  to  de- 
termine the  length  of  wire,  such  that  the  number  of  grams  of  coating 
will  represent  the  number  of  ounces  per  square  foot  of  surface.  These 
lengths  are  given  in  Table  I.  In  the  lighter  wires,  however,  it  will 
be  found  convenient  to  use  some  fraction  of  these  lengths. 

The  method  of  making  the  test  is  very  similar  to  that  outlined 
for  galvanized  sheets,  except  that  the  wire  is  first  cleaned  writh  carbon 
tetrachloride  or  gasoline,  and  after  being  carefully  weighed  is  placed 
in  a  tall  glass  cylinder  containing  hydrochloric  acid  (sp.  gr.  1.20),  to 
which  has  been  added  from  2  to  3  cc.  of  antimony-chloride  solution  of 
the  same  strength  as  used  on  galvanized  sheets.  The  reason  for 
using  one-half  the  amount  of  antimony  chloride  in  the  case  of  wire  is 
on  account  of  taking  one-half  the  area. 

As  previously  stated,  the  coating  on  galvanized  sheets  in  ex- 
pressed in  ounces  per  square  foot,  considering  one  side  only,  when  in 
reality  this  amount  of  coating  represents  two  square  feet  of  surface. 
After  immersing  the  entire  length  of  wire  for  one  minute  it  will  be 
found  convenient  to  pour  the  acid  solution  into  another  tall  cylinder 
in  order  to  facilitate  removing  the  wire.  The  wire  is  then  scrubbed 
under  running  water,  wiped,  thoroughly  dried  in  a  warm  place  for  a 
few  seconds  and  again  weighed.  Each  gram  lost  corresponds  to  1  oz. 
of  coating  per  square  foot.  For  direct  comparison  with  the  weight 
of  coating  as  expressed  on  galvanized  sheets,  this  figure  should  be 
doubled. 


186 


SPELTER  COATING 


//  Discard 


2.0B8 
2.045 
2.086 
2,057 
2,07 


Av.  2.071 


Edge. 


Width  of  Sheet 


20/4 
1.993 

2.065 
2.1  U 

2.12 


2.129 
2,067 


Av.  2.060 
Sheet  Average  •  ?.  082 

Center. 


Av.z.ns 

Edge, 


Note  •-  For  Commercial  Testing,  Squares  A,  B  and  C  may  be  Used. 

Numerals  Represent  Weight  of  Zinc  Coating  in  ounces  persquare 'foot 


SPELTER  COATING  187 


TABLE  I 

LENGTHS  OF  WIRE  TO  GIVE  GRAMS  OF  COATING  EQUIVALENT 

TO  OUNCES  PER  SQUARE  FOOT 

Length  for  Test 
Diameter, 

Gauge  No.                               in.  in.  cm. 

0  0.340  4-12/16  12.1 

1  0.300  5-  6/16  13.7 

2  0.284  5-11/16  14.5 

3  0.259  6-4/16  15.9 

4  0.238  6-13/16  17.3 

5  0.220  7-6/16  18.7 

6  0.203  7-15/16  20.2 

7  0.180  9  22.8 

8  0.165  9-13/16  .24.9 

9  0.148  10-15/16  27.7 

10  0.134  12-  1/16  30.6 

11  0.120  13-  8/16  34.2 

12  0.109  14-13/16  37.7 

13  0.095  17  43.2 

14  0.083  19-  8/16  49.5 

15  0.072  22-  7/16  57.0 

16  0.065  24-14/16  63.2 

17  0.058  27-14/16  70.8 

18  0.049  33  83.8 


188 


SPELTER  COATING 


* 


SPELTER  COATING  189 

DETERMINATION  OF  SPELTER  COATING 
LEAD  ACETATE  METHOD 

This  test  is  based  upon  the  fact  that  when  a  zinc  coated  article 
is  placed  in  lead  acetate  at  ordinary  temperatures,  the  zinc  passes  into 
solution,  and  an  equivalent  amount  of  metallic  lead  is  precipitated 
in  a  loosely  adherent  form  upon  the  specimen.  The  reaction  is 
retarded  by  the  precipitation  of  the  lead  and,  therefore,  when  a  heavily 
galvanized  piece  is  being  tested,  this  lead  must  be  periodically  re- 
moved. The  lead  acetate  solution  can  be  used  as  the  Preece  copper 
sulphate  test  if  desired.  That  is  to  measure  the  number  of  immer- 
sions which  are  required  to  remove  all  of  the  galvanized  coatings. 
Should  lead  plate  on  the  surface  of  the  sample  it  is  not  easily  con- 
founded with  the  bright  iron  when  exposed.  The  uncovering  of  the 

iron  can  be  readily  detected.      The  test  is  made  as  follows: 

i 

Three  samples,  2/4  x  2J4"  are  cut  from  a  galvanized  sheet  as 
described  in  the  previous  method.  The  samples  are  weighed  to- 
gether and  submerged  separately  for  three  minutes  in  tumblers  con- 
taining the  lead  acetate  solution.  Tumblers  are  recommended  on 
account  of  the  fact  that  they  are  just  the  right  diameter  to  enable  the 
samples  to  be  maintained  in  an  upright  position. 

After  submerging  for  three  minutes  the  samples  are  taken  out 
and  the  adherent  lead  removed  with  a  stiff  brush  or  steel  spatula. 
A  burnishing  action  should  be  avoided,  as  under  some  conditions 
closely  adherent  lead  will  be  plated  out  on  the  iron.  Repeat  the 
three  minute  immersions  in  the  lead  acetate  solutions  until  a  bright 
surface  is  exposed.  Four,  3-minute  immersions  are  usually  sufficient. 
Wash  specimens  in  water,  dry,  warm  slightly,  allow  to  cool  and  weigh. 
The  loss  in  grams  divided  by  the  number  of  samples  taken  represents 
the  weight  of  coating  in  ounces  per  square  foot. 

The  lead  acetate  solution  is  prepared  by  dissolving  400  grams  of 
crystallized  lead  acetate  in  1  liter  of  water.  When  dissolved,  add 
4  grams  of  finely  powdered  litharge  and  agitate  until  most  of  it  has 
dissolved.  The  solution  is  allowed  to  settle  and  the  clear  portion 
decanted  for  use. 

The  Hydrochloric  Acid  Antimony  Chloride  Method  is  more 
reliable  than  this  method,  takes  less  time,  and  has  been  recommended 
as  the  standard  method. 


190 


SPELTER  COATING 


•si 


•fs  e  ^ 

"^   O    tf) 

•*->  a  oj 


- 


i      tn 

.19 
S3 


g.s 

• /.  — 

o 


bfl 
C 

I 
• 


SULPHUR  191 


SULPHUR 

DETERMINATION  OF  SULPHUR 
/  BY  EVOLUTION 

Dissolve  5  grams  of  the  sample  in  100  cc.  of  hydrochloric  acid, 
1.10  specific  gravity,  contained  in  a  500  cc.  flask  fitted  with  rubber 
stopper  containing  thistle  tube  and  educt  tube,  passing  through  a 
reflux  condenser  to  prevent  acid  distilling  over. 

The  educt  tube  dips  almost  to  the  bottom  of  a  10"xl"  test  tube 
containing  50  cc.  of  cadmium  chloride  solution.  A  low  flame  is 
applied  and  flask  heated  until  all  metal  has  dissolved  and  all  gas  has 
been  driven  out  of  flask,  as  is  evidenced  by  the  steam  condensing  in 
cadmium  chloride  tube.  The  contents  of  test  tube  are  washed  into 
an  800  cc.  beaker  and  sufficient  water  is  added  to  bring  the  volume 
to  500  cc.  Add  2  cc.  of  starch  solution  and  50  cc.  of  hydrochloric 
acid,  1.20  specific  gravity.  The  solution  is  then  titrated  with  standard 
iodine  solution  to  blue  color. 

The  standard  iodine  solution  is  prepared  by  dissolving  8.4  grams 
of  iodine  and  20  grams  of  potassium  iodide  in  50  cc.  of  distilled  water. 
When  iodine  is  in  solution  dilute  to  2  liters  and  standardize  with  steel 
of  known  sulphur  content.  One  cc.  should  equal  .01%  of  sulphur 
when  using  5  grams. 

A  solution  of  potassium  iodate  (KIO3)  can  be  used  instead  of  the 
iodine  and  potassium  iodide  just  described.  The  potassium  iodate 
is  more  stable. 

The  Starch  Solution  can  be  prepared  along  any  of  the  following 
lines: 

(1)  One  gram  arrowroot  mixed  in  10  cc.  of  cold  water  which  is 
poured  into  100  cc.  of  boiling  water  and  immediately  removed  from 
the  source  of  heat. 

(2)  Dissolve  20  grams  of  soluble  starch  in  100  cc.  of  distilled 
water  to  which  can  be  added  40  grams  of  potassium  iodide,  free  from 
iodine. 

This  mixture  is  then  poured  into  900  cc.  of  distilled  water.  Potas- 
sium iodide  makes  the  starch  more  sensitive  and  it  should  not  require 


192 


SULPHUR 


more  than  .2  of  a  cc.  of  iodine  to  give  a  permanent  blue  color  in  water 
containing  a  small  amount  of  hydrochloric  acid. 

(3)  If  soluble  starch  is  not  available,  corn  starch  can  be  used  as 
follows : 

To  a  mixture  of  10  grams  of  corn  starch  and  50  cc.  of  distilled 
water,  slowly  add  a  solution  containing  5  grams  of  caustic  potash 
and  50  cc.  of  distilled  water,  until  the  starch  changes  to  a  clear  paste. 
Dilute  to  500  cc.  with  distilled  water  and  add  10  grams  of  potassium 
iodide  crystals,  free  from  iodine. 

(4)  Prepare  500  cc.  of  a  saturated  solution  of  sodium  chloride, 
and  also  a  solution  containing  100  cc.  of  80%  acetic  acid  in  which  5 
grams  of  starch  has  been  dissolved.       Pour  into  the  sodium  chloride 
solution  and  boil  until  clear.       Make  up  to  600  cc.  with  distilled 
water,  using  2  cc.  for  each  determination  of  sulphur. 


Chemist  pulverizing  sample  of  coal  for  chemical  analysis 


SULPHUR  193 

DETERMINATION  OF  SULPHUR 
GRAVIMETRIC  METHOD 

We  prefer  the  Gravimetric  Method  for  the  determination  of 
sulphur  where  great  accuracy  is  desired.  We  use  the  Bureau  of 
Standards'  method  which  is  essentially  as  follows: 

Dissolve  the  sample  (4.57  grams)  in  250  cc.  of  copper-potassium 
chloride  solution  (300  g.  KCL-CuCl2  and  100  cc.  HC1  per  liter)  and 
filter  the  residue  on  asbestos.  Wash  2  or  3  times  with  5%  hy- 
drochloric acid  and  then  return  residue  and  asbestos  pad  to  the  beaker 
and  treat  with  20  cc.  of  nitric  acid  (Sp.  Gr.  1.42).  Heat  and  add 
KC1O3  until  all  carbonaceous  matter  is  destroyed. 

Add  a  little  (5  cc.)  hydrochloric  acid  to  dissolve  the  precipitated 
manganese  dioxide  and  filter  through  asbestos  again.  Evaporate 
the  solution  to  dry  ness,  take  up  in  10  cc.  of  hydrochloric  acid  and 
evaporate  to  dryness  again.  Take  up  in  5  cc.  of  2%  hydrochloric 
acid  and  20  cc.  of  water  and  filter  through  paper.  Precipitate  the 
sulphuric  acid  in  the  boiling  filtrate  with  2  cc.  of  hot  10%  barium 
chloride  solution.  Digest  a  short  time  on  the  hot  plate  and  filter. 
Wash  the  barium  sulphate  with  water  until  free  from  chlorides,  ignite 
slowly,  and  weigh.  The  weight  of  barium  sulphate  in  grams  multi- 
plied by  3  is  equal  to  the  percentage  of  sulphur. 


194 


SULPHUR 


100,000  Ib.  Riehle  Testing  Machine,  showing  arrangements  for  carrying  out  tensile 
tests  at  high  temperature 


• 


SULPHUR  195 

DETERMINATION  OF  SULPHUR 
OXIDATION  METHOD 

In  a  400  cc.  beaker  dissolve  5  grams  of  the  steel  in  a  mixture  of 
40  cc.  of  nitiic  acid,  (Sp.  Gr.  1.42)  and  5  cc.  of  hydrochloric  acid, 
(Sp.  Gr.  1.20)  add  0.5  grams  of  sodium  carbonate  and  evaporate  the 
solution  to  dryness.  Add  40  cc.  of  hydrochloric  acid,  (Sp.  Gr.  1.20) 
evaporate  to  dryness  and  bake  at  a  moderate  heat.  After  solution 
of  the  residue  in  30,cc.  of  hydrochloric  acid,  (Sp.  Gr.  1.20)  and  evapora- 
tion to  syrupy  consistency,  add  2  to  4  cc.  of  hydrochloric  acid  (Sp.  Gr. 
1.20),  and  then  30  to  40  cc.  of  hot  water. 

Filter  and  wash  with  cold  water,  the  final  volume  not  exceeding 
100  cc.  To  the  cold  filtrate  add  10  cc.  of  the  barium  chloride  solution. 
Let  stand  at  least  24  hours,  filter  on  a  9-cm.  paper,  wash  the  precipitate 
first  with  a  hot  solution  containing  10  cc.  of  hydrochloric  acid,  (Sp. 
Gr.  1.20),  and  1  gram  barium  chloride  to  the  liter,  until  free  from 
iron;  and  then  with  hot  w^ater  till  free  from  chloride.  Ignite  and 
weigh  as  barium  sulphate. 

Keep  the  washings  separate  from  the  main  filtrate  and  evaporate 
them  to  recover  any  dissolved  barium  sulphate. 

NOTE:  A  blank  determination  on  all  reagents  used  should  be 
made  and  the  results  corrected  accordingly. 

Barium  Chloride 

Dissolve  100  grams  of  barium  chloride  in  1000  of  distilled  water. 


SULPHUR 


PhysicaljTesting'Machine  capacity  100,000  Ibs.,  illustrating  method  used  for  checking 
the  accuracy  of  the  machine 


TIN  AND  TERNE  PLATE  197 


TIN  PLATE 

METHOD  FOR  SAMPLING  AND  ANALYSIS  OF  TIN, 
TERNE  AND  LEAD-COATED  SHEETS 

Four  2  by  4-in.  pieces  are  cut,  one  from  each  end  and  each  side 
of  the  sheet,  parallel  with  the  sides  and  equidistant  from  the  ends, 
as  shown  on  Page  198.  One  sheet  from  each  grade  or  shipment  is 
taken  for  analysis. 

These  samples,  before  weighing,  should  be  thoroughly  cleaned 
with  chloroform,  carbon  tetrachloride  or  gasoline.  Each  piece  is 
then  cut  in  half,  marking  one  half  "A"  and  the  other  half  "B".  The 
four  pieces  comprising  lot  A  are  then  accurately  weighed  together, 
cut  into  small  pieces  about  Y%  in.  square,  thoroughly  mixed,  and  used 
for  the  determination  of  tin  and  lead.  The  four  pieces  comprising 
lot  B  are  reserved  for  the  analysis  of  base  metal  and  the  direct  de- 
termination of  coating  as  a  check  on  the  analysis  of  lot  A. 

A  templet  should  be  provided,  made  preferably  from  steel  Y%  in. 
thick  and  exactly  2  by  4  in.  A  scribe  is  used  to  accurately  mark  the 
sections  to  be  cut.  The  templet  is  then  used  to  subdivide  the  2  by 
4  in.  specimens  into  two  pieces,  2  by  2  in.  The  sections  for  analysis 
are  then  cut  with  tinner's  shears. 

METHOD  OF  ANALYSIS 
DETERMINATION  OF  TIN 

Three  5-gram  portions  of  the  finely  cut  sample  of  lot  A  are  placed 
into  three  300  cc.  Erlenmeyer  flasks,  each  fitted  with  a  one-hole  rubber 
stopper  containing  a  glass  tube  bent  twice  at  right  angles,  one  end 
of  which  projects  through  the  rubber  stopper  for  a  short  distance, 
the  other  end  being  long  enough  to  reach  almost  to  the  bottom  of  a 
beaker,  placed  on  a  level  with  the  flask,  containing  about  300  cc.  of 
dilute  sodium-bicarbonate  solution.  Add  75  cc.  of  concentrated 
hydrochloric  acid,  connect  the  flask  with  the  stopper  containing  the 
glass  tube,  and  place  the  flask  on  a  hot-plate.  Heat  gradually  at 
first  until  most  of  the  metal  is  in  solution.  The  long  end  of  the  glass 
tube,  in  the  meantime,  is  submerged  in  the  beaker. 


198 


TIN  AND  TERNE  PLATE 


-r 


*T-# 


4\ 

!  % 

_v 


<- 


> 


>l 


TIN  AND  TERNE  PLATE  199 

The  hydrochloric  acid  solution  is  finally  brought  to  boiling  and 
when  all  the  metal  is  dissolved  the  beaker  containing  dilute  sodium- 
bicarbonate  solution  is  replaced  by  one  containing  a  saturated  solution 
of  the  same.  Remove  the  beaker  and  flask  to  a  cool  place. 
This  will  cause  a  small  amunt  of  the  sodium-bicarbonate  to 
enter  the  flask  and  exclude  the  air.  The  solution  is  finally  brought 
to  a  low  temperature,  preferably  with  ice  water.  This  solution  is 
then  diluted  to  about  200  cc.  with  oxygen-free  water  which  contains 
several  cubic  centimeters  of  starch  solution,  and  titrated  with  N/20 
iodine  solution.  We  have  found  this  strength  of  iodine  solution  to  be 
the  most  satisfactory  for  this  method. 

The  distilled  water  free  from  oxygen  is  obtained  in  any  of  three 
ways:  (1)  By  passing  carbon  dioxide  through  the  cold  distilled  water; 
(2)  By  boiling  vigorously  and  cooling;  or  (3)  by  adding  a  few  cubic 
centimeters  of  concentrated  hydrochloric  acid  to  the  water  and  then 
about  2  g.  of  sodium  bicarbonate  stirring  vigorously.  By  running 
this  determination  in  triplicate,  the  first  titration  serves  as  a  control 
to  indicate  the  number  of  cubic  centimeters  of  iodine  required,  whence 
the  two  succeeding  titrations  may  be  made  very  rapidly  and  should 
check  very  closely. 

Standardizing  the  Iodine  Solution: 

About  0.1  g.  of  pure  tin  and  4  g.  of  iron  filings  are  dissolved  in 
75  cc.  of  concentrated  hydrochloric  acid,  etc.,  as  under  the  determina- 
tion of  tin.  One  cubic  centimeter  of  TV/20  iodine  =  0.002975  g. 
of  tin. 

Calculation — Weight  of  tin' 

Wt.  of  tin  on  5  g.  x  Wt.  (g.)  of  16  sq.  in. 

-  x  8.6421   =  number  of 

5 

pounds  per  case  of  112  sheets,  20  by  28  in. 

DETERMINATION  OF  LEAD 

Dissolve  10  g.  of  the  finely  cut  sample  of  lot  A  in  150  cc.  of  nitric 
acid  (1:1).  Heat  until  free  from  brown  fumes  and  dilute  to  1  liter 
and  mix  thoroughly.  Take  100  cc.  of  this  solution,  add  10  cc.  of 
concentrated  nitric  acid,  electrolyze  at  a  temperature  of  50  to  60°  C., 
using  1  to  2  amperes  and  2.3  to  2.5  volts.  The  weight  of  PbO2  is 
multiplied  by  0.866. 


200  TIN  AND  TERNE  PLATE 

If  the  base  metal  contains  an  appreciable  amount  of  manganese 
the  lead  should  be  determined  as  sulfate. 

Calculation — Weight  of  lead: 

PbO2  found  (g.)  x  0.866  x  10  =  Pb; 

Pb  x  Wt.  (g.)  of  16  sq.  in. 

—x  8.6421  =  number  of  pounds 

per  case  of  112  sheets,  20  by  28  in. 


DIRECT  DETERMINATION  OF  THE  WEIGHT 
OF  COATING 

The  remaining  four  pieces  representing  lot  B  are  used  for  the 
analysis  of  the  base  metal  and  incidentally  can  be  used  for  the  direct 
determination  of  the  weight  of  coating. 

The  four  2  by  2-in.  pieces  are  carefully  weighed  together  and  each 
piece  is  wrapped  with  a  stiff  platinum  or  nickel  wire  in  such  a  manner 
that  it  may  be  placed  in  the  acid  in  a  horizontal  position.  Heat  60 
cc.  of  concentrated  sulphuric  acid  contained  in  a  400-cc  Jena  glass 
beaker  to  at  least  250°  C.,  immerse  each  piece  separately  in  the  hot 
acid  for  exactly  1  minute,  and  remove  to  a  600-cc.  Jena  beaker  con- 
taining 50  cc.  of  distilled  water.  Immerse  momentarily  and  rub  the 
surface  while  washing  with  about  50  cc.  more  of  distilled  water,  using 
a  wash  bottle  for  this  purpose.  The  four  samples  are  thoroughly 
dried,  reweighed,  and  used  for  the  analysis  of  base  metal. 

The  loss  .in  weight  represents  the  coating  and  some  iron.  The 
sulphuric  acid  contained  in  the  400  cc.  beaker  is  cooled  and  combined 
with  the  washings  in  the  600  cc.  beaker.  Two  hundred  cubic  centi- 
meters of  concentrated  hydrochloric  acid  are  added  and  the  solution 
boiled  for  a  few  minutes.  The  solution  is  cooled,  poured  into  a  gradu- 
ated 500  cc.  flask  and  filled  to  the  mark  with  distilled  water. 

DETERMINATION  OF  IRON 

Place  lOOcc.  of  this  solution  in  a  300cc.  Erlenmeyer  flask,  add  1  cc. 
of  a  standard  solution  of  potassium  permanganate  to  oxidize  the  iron 
and  tin,  heat  to  boiling  and  reduce  with  a  few  drops  of  stannous 
chloride.  Cool,  pour  into  a  liter  beaker  containing  400  cc.  of  dis- 
tilled water,  add  25  cc.  of  mercuric  chloride,  followed  by  10  cc.  of 
phosphoric  acid  and  manganese-sulphate  solution,  and  titrate  with 
TV/10  potassium  permanganate. 


TIN  AND  TERNE  PLATE  201 

Calculation — 

Four  pieces  2  by  2  in.  weigh 28.5686  g. 

Same  after  stripped  in  acid 24.1620  g. 

Loss,  coating  plus  iron 4.4066  g. 

Iron  as  found  by  titration 0.4887  g. 

Weight  of  coating 3.9179  g. 

3.9179  x  8.6421  =  number  of  pounds  per  case  of  112  sheets, 
20  by  28  in. 

Tin  in  100  cc.  x  5  x  100 

—  =  percentage  of  tin. 
Weight  of  Coating 

Percentage  of  lead  is  obtained  by  difference. 

In  the  analysis  of  tin  plate,  the  weight  of  coating  is  expressed  in 
pounds  per  box,  which  is  a  half  case,  or  112  sheets  14  by  20  in.;  hence 
to  obtain  the  weight  of  coating  per  box  on  tin  plate,  the  number  of 
pounds  as  obtained  above  is  divided  by  two. 

CHECK  DETERMINATION  OF  TIN 

The  remainder  of  the  solution  which  has  been  used  for  the  de- 
termination of  iron  can  be  used  for  the  determination  of  tin  as  follows : 
Place  three  portions  of  100  cc.  each  in  three  300  cc.  Erlenmeyer  flasks. 
If  any  of  the  lead  sulphate  should  or  should  not  be  removed  in  any  of 
these  portions,  the  accuracy  of  the  tin  determination  is  not  affected. 
Add  1  g.  of  powdered  antimony,  connect  with  rubber  stopper  and  glass 
tube  described  in  the  method  of  determination  of  tin  in  the  sample 
of  lot  A,  place  on  a  hot-plate,  using  dilute  sodium  biarbonate  solution 
as  a  trap,  and  boil  until  the  solution  becomes  decolorized.  Replace 
the  dilute  sodium-bicarbonate  solution  with  a  saturated  solution  of 
the  same,  remove  from  the  hot-plate,  cool,  dilute  and  complete  the 
determination  as  described  under  the  first  method. 

CONCLUSIONS 

We  claim  for  this  method  that  the  sample  shows  a  true  average 
of  the  coating  on  the  plate,  since  we  have  checked  the  coating  very 
closely  by  this  method  and  by  sampling  from  the  center  of  the  sheet, 
even  with  such  large  samples  as  10  by  10  in.  When  5  g.  of  the  sample  are 
taken  for  the  determination  of  tin,  an  area  of  about  2.5  sq.  in.  is  re- 
presented in  the  case  of  40-lb.,  1C  plate,  and  of  about  3  sq.  in.  in  the 
case  of  25-lb.  plate;  while,  of  course,  it  is  double  this  in  the  determina- 
tion of  lead.  Furthermore,  the  amount  of  sample  taken  here  for 


202  TIN  AND  TERNE  PLATE 

analysis  is  a  representative  quantity  from  16  sq.  in.  and  not  merely 
from  one  particular  section  of  2.5  of  3  sq.  in.;  and  is  as  large  as  many 
laboratories  are  using  and  larger  than  most  are  using. 

In  addition,  we  believe  that  this  method  is  more  truly  average 
than  any  method  we  have  investigated;  and  moreover,  the  sheet  is  not 
destroyed  so  far  as  usefulness  is  concerned,  but  may  be  sheared  down 
to  a  smaller  size.  While  it  is  not  necessary  to  determine  the  weight 
of  coating  directly  by  the  sulphuric  acid  method,  in  addition  to  the 
determination  of  the  lead  and  tin  (on  lot  A),  it  will,  however,  serve 
as  a  check,  and  should  ^.gree  very  closely  with  it.  Furthermore,  this 
is  an  excellent  method  for  stripping  the  coating  preliminary  to  the 
analysis  of  the  base  metal. 

By  running  the  determination  of  tin  in  triplicate,  as  described, 
the  method  is  very  rapid  and  accurate,  whereas  the  method  as  now 
used  by  many  laboratories  in  which  the  plate  is  dissolved  in  an  atmos- 
phere of  carbon  dioxide  in  a  graduated  flask,  cooled,  diluted  to  volume 
and  titrated  in  aliquots,  involves  many  details  and  is  not  so  rapid. 
In  this  method  also,  no  antimony  is  needed  for  the  reduction  of  tin, 
since  the  iron  in  the  base  metal  accomplishes  this;  moreover,  in  the 
presence  of  the  quantity  of  tin  here  involved  the  antimony  would 
have  a  tendency  to  deposit  back  on  the  plate,  retarding  the  solution 
of  the  tin  and  thus  giving  low  results. 

With  the  use  of  a  rotating  anode  the  proposed  method  is  very 
rapid  and  the  entire  determination  can  be  finished  in  a  reasonable 
length  of  time. 


TITANIUM  203 


TITANIUM 

BUREAU  OF  STANDARDS'  METHOD  FOR  THE 
DETERMINATION  OF  TITANIUM 

Titanium  is  determined  by  treating  5  grams  of  iron  with  40  cc. 
of  hydrochloric  acid  (1:1)  and  heating  until  all  iron  has  gone  into  solu- 
tion. Dissolving  in  this  manner,  all  but  a  negligible  quantity  of 
titanium  remains  in  the  insoluble  residue.  The  filtrate  is  tested  for 
titanium  by  extracting  the  iron  with  ether  after  oxidation  with  a  small 
amount  of  nitric  acid,  using  the  method  of  Rothe  (Stahl  und  Eisen, 
12,  1052  (1892),  and  13,  333  (1893),)  and  adding  hydrogen  peroxide 
to  the  extracted  solution,  after  expelling  the  ether  and  oxidizing  with 
nitric  acid.  In  all  cases  only  a  faint  coloration  is  obtained.  The 
insoluble  residue  is  filtered  off  and  washed  with  hot  water,  and  the 
filter  paper  and  carbonaceous  matter  are  burned. 

The  residue  in  the  crucible  is  treated  with  hydrofluoric  acid  and 
a  little  sulphuric  acid,  and  all  silicon  volatilized.  The  residue  is 
fused  with  sodium  carbonate,  treated  with  water,  and  acidified  with 
sulphuric  acid. 

A  sufficient  amount  of  ferric  alum  is  added  to  the  standard 
titanium  solution  to  give  the  same  tint  as  the  sample  when  they  are 
at  the  same  time  dilution,  for  it  is  found  that  the  residue  from  the 
silica  always  contains  a  little  iron  along  with  the  titanium.  Hydrogen 
peroxide  is  added  to  the  solution  and  standard  and  the  comparison 
made  in  a  Wolff  colorimeter. 

Reagents 
Peroxide  Solution: 

Dissolve  4  grams  of  sodium  peroxide  in  125  cc.  dilute  sulphuric 
acid  (1  of  acid  to  3  of  water),  and  dilute  to  500  cc. 

Concentrated  Standard  Titanium  Solution: 

One-fourth  gram  of  a  standard  20%  carbonless  ferro-titanium  is  dis- 
solved in  30  cc.  of  dilute  sulphuric  acid  (1  acid  to  3  water).  When  so- 
lution is  complete  it  is  oxidized  by  the  least  possible  quantity  of  con- 
centrated nitric  acid,  boiled  for  a  few  minutes,  cooled  and  diluted  to 


204  TITANIUM 

such  a  volume  that  1  cc.  will  contain  0.0005  gram  of  titanium.     When 
using  a  five-gram  sample  1  cc.  is  therefore  equal  to  0.01%  titanium. 

Dilute  Standard  Titanium  Solution: 

This  solution  is  made,  just  before  making  the  determination, 
by  diluting  one  volume  of  the  concentrated  standard  titanium 
solution  to  ten  volumes. 

One  cc.  of  this  solution  contains  0.00005  gram  of  titanium  and 
is  equal  to  0.001%  of  titanium  when  using  a  5-gram  sample. 


VANADIUM  205 


VANADIUM 

DOUGHERTY'S1  METHOD  FOR  THE  DETERMINATION 
OF  VANADIUM  IN  STEEL 

In  the  application  of  Johnson's2  or  similar  methods  for  the 
determination  of  vanadium  in  steel,  considerable  difficulty  is  often 
experienced  in  producing  a  colorless  or  "old  rose"  shade  with  ferrous 
sulphate  in  the  solution  containing  an  excess  of  permanganate  after 
the  preliminary  oxidation  of  the  vanadium.  To  obviate  this  diffi- 
culty the  following  method  has  been  developed,  in  which  this  oxida- 
tion of  the  vanadium  is  effected  by  a  sufficient  quantity  of  nitric  acid 
alone  or  with  ammonium  persulphate. 

Method 

Treat  2  to  4  grams  of  the  drillings  in  a  500  cc.  Erlen- 
meyer  flask,  with  60  cc.  of  water  and  10  cc.  of  concentrated 
sulphuric  acid.  After  heating  the  solution  nearly  to  boiling,  until 
the  reaction  is  complete,  add  40  cc.  of  nitric  acid  (Sp.  Gr.  1.20),  and 
boil  thoroughly  for  10  minutes  to  oxidize  the  iron  and  vanadium  and 
to  expel  the  last  traces  of  nitrous  fumes. 

Cool  the  solution,  add  60  cc.  of  cold  sulphuric  acid  (1:2)  and 
dilute  in  a  600  cc.  beaker  to  450  cc.  Add  3  cc.  of  a  freshly  prepared 
1%  solution  of  potassium  ferricyanide,  and  titrate  rather  rapidly, 
with  constant  stirring,  with  N/20  ferrous  ammonium  sulphate,  to 
the  appearance  of  the  first  dark  blue  color.  The  end  point  can  best 
be  observed  by  looking  through  the  side  of  the  beaker  toward  the 
bottom  of  the  beaker  placed  directly  before  a  window.  Deduction 
of  a  blank  of  0.4  cc.  of  the  ferrous  solution  has  been  found  necessary, 
and  is  independent  of  the  weight  of  the  sample,  the  presence  of 
chromium,  and  of  the  carbon  content  up  to  0.5  per  cent. 

For  steels  with  over  0.50  per  cent  carbon,  the  blanks  are  higher; 
and,  moreover,  with  4-gram  samples  of  such  steels,  the  end  point  is 
rendered  indistinct  by  a  turbidity  which  appears  toward  the  end  of 
the  titration.  This  difficulty  may  be  avoided  by  adding  to  the  solu- 
tion immediately  after  the  boiling  with  nitric  acid  as  above,  60  cc. 
of  1:2  sulphuric  acid  and  5  to  8  grams  of  ammonium  persulphate 
(which  in  the  absence  of  silver  nitrate  will  not  oxidide  the  Cr.  and 
Mn.),  and  continuing  to  boil  for  15  minutes,  so  that  all  nitrous  oxides 
and  hydrogen  peroxide  are  expelled.  (Before  this  second  boiling, 

George  T.  Dougherty,  The  Journal  of  Industrial  and  Engineering  Chemistry,  May,  1915. 
2  C.  M.  Johnson,  "Analysis  of  Special  Steels." 


206  VANADIUM 

wash  down  with  hot  water  the  persulphate  which  sticks  to  the  glass.) 
Cool,  dilute  and  titrate  as  above.  After  such  treatment  the  blank  is 
.35  cc.  (instead  of  .4  cc.)  for  steels  with  under  .5  per  cent  carbon,  and 
.5  cc.  for  .60  to  .70  carbon,  and  .6  cc.  for  .90  to  1.25  carbon  steels. 

The  blanks  are  the  same  with  or  without  the  persulphate  treat- 
ment for  steels  of  over  .50  per  cent  carbon. 

The  ferrous  ammonium  sulphate  solution  may  be  standardized 
against  N/W  permanganate,  the  strength  of  which  has  been  de- 
termined with  sodium  oxalate.  The  iron  value  of  the  permanganate 
multiplied  by  .917  gives  the  vanadium  value. 

If  chromium  is  desired  it  should  be  determined  on  a  separate 
portion,  using  the  sodium  bismuthate  oxidation  method. 


USEFUL  DATA  207 


USEFUL  DATA 

To  find  circumference  of  a  circle  multiply  diameter  by  3.1416. 
To  find  diameter  of  a  circle  multiply  circumference  by  .31831. 
To  find  area  of  a  circle  multiply  square  of  diameter  by  .7854. 
To  find  area  of  a  triangle  multiply  base  by  J/2  perpendicular  height. 
To  find  surface  of  a  sphere  multiply  square  of  diameter  by  3.1416. 
To  find  solidity  of  a  sphere  multiply  cube  of  diameter  by  .5236. 
Doubling  the  diameter  of  a  pipe  increases  its  capacity  four  times. 

A  gallon  of  water  (U.  S.  Standard)  weighs  8  Ibs.  /^  oz.,  and  con- 
tains 231  cubic  inches. 


A  cubic  foot  of  water  contains  1728  cubic  inches,  iy%  gallons  and 
weighs  621/2  pounds. 

A  standard  horse  power  :  The  evaporation  of  30  pounds  of  water 
per  hour  from  a  feed  water  temperature  of  100  deg.  F.,  into  steam 
at  70  pounds  gauge  pressure. 

To  find  capacity  of  tanks  any  size;  given  dimensions  of  a  cylinder 
in  inches,  to  find  its  capacity  in  U.  S.  gallons:  Square  the  diameter, 
multiply  by  the  length  and  by  .0034. 

1  meter  =  39.37  inches. 

2.54  cm.  =  1  inch 

28316  cc.  =  1  cubic  foot. 

29.573  cc  =  1  fluid  oz. 

1000  cc.  =  1.05668  quarts. 

3785.43  cc.  =  1  U.  S.  Gallon  (231  cu.  in.) 

1  gram  =  15.4324  grains  =  .035274  oz.  avoirdupois. 

1  kilo  =  2.2046  pounds  (avoirdupois). 

28.35  grams  =  1  oz. 

453.59  grams  =  1  pound. 


208 


USEFUL  DATA 


CONVERSION   TABLES   OF   FAHRENHEIT   AND    CENTIGRADE 

SCALES 


Cent. 

Fahr. 

Cent. 

Fahr. 

Cent. 

Fahr. 

Cent. 

Fahr. 

Cent. 

Fahr. 

0 

32 

200 

392 

400 

752 

600 

1112 

800 

1472 

5 

41 

205 

401 

405 

761 

605 

1121 

805 

1481 

10 

50 

210 

410 

410 

770 

610 

1130 

810 

1490 

15 

59 

215 

419 

415 

779 

615 

1139 

815 

1499 

20 

68 

220 

428 

420 

788 

620 

1148 

820 

1508 

25 

77 

225 

437 

425 

797 

625 

1157 

825 

1517 

30 

86 

230 

446 

430 

806 

630 

1166 

830 

1526 

35 

95 

'235 

455 

435 

815 

635 

1175 

835 

1535 

40 

104 

240 

464 

440 

824 

640 

1184 

840 

1544 

45 

113 

245 

473 

445 

833 

645 

1193 

845 

1553 

50 

122 

250 

482 

450 

842 

650 

1202 

850 

1562 

55 

131 

255 

491 

455 

851 

655 

1211 

855 

1571 

60 

140 

260 

500 

460 

860 

660 

1220 

860 

1580 

65 

149 

265 

509 

465 

869 

665 

1229 

865 

1589 

70 

158 

270 

518 

470 

878 

670 

1238 

870 

1598 

75 

167 

275 

527 

475 

887 

675 

1247 

875 

1607 

80 

176 

280 

536 

480 

896 

680 

1256 

880 

1616 

85 

185 

285 

545 

485 

905 

685 

1265 

885 

1625 

90 

194 

290 

554 

490 

914 

690 

1274 

890 

1634 

95 

203 

295 

563 

495 

923 

695 

1283 

895 

1643 

100 

212 

300 

572 

500 

932 

700 

1292 

900 

1652 

105 

221 

305 

581 

505 

941 

705 

1301 

905 

1661 

110 

230 

310 

590 

510 

950 

710 

1310 

910 

1670 

115 

239 

315 

599 

515 

959 

715 

1319 

915 

1679 

120 

248 

320 

608 

520 

968 

720 

1328 

920 

1688 

125 

257 

325 

617 

525 

977 

725 

1337 

925 

1697 

130 

266 

330 

626 

530 

986 

730 

1346 

930 

1706 

135 

275 

335 

635 

535 

995 

735 

1355 

935 

1715 

140 

284 

340 

644 

540 

1004 

740 

1364 

940 

1724 

145 

293 

345 

653 

545 

1013 

745 

1373 

945 

1733 

150 

302 

350 

662 

550 

1022 

750 

1382 

950 

1742 

155 

311 

355 

671 

555 

1031 

755 

1391 

955 

1751 

160 

320 

360 

680 

560 

1040 

760 

1400 

960 

1760 

165 

329 

365 

689 

565 

1049 

765 

1409 

965 

1769 

170 

338 

370 

698 

570 

1058 

770 

1418 

970 

1778 

175 

347 

375 

707 

575 

1067 

775 

1427 

975 

1787 

180 

356 

380 

716 

580 

1076 

780 

1436 

980 

1796 

185 

365 

385 

725 

585 

1085 

785 

1445 

985 

1805 

190 

374 

390 

734 

590 

1094 

790 

1454 

990 

1814 

195 

383 

395 

743 

595 

1103 

795 

1463 

995 

1823 

USEFUL  DATA 


209 


CONVERSION  TABLES  OF  FAHRENHEIT  AND  CENTIGRADE 
SCALES 


Cent. 

Fahr. 

Cent. 

Fahr. 

Cent. 

Fahr. 

Cent. 

Fahr. 

1000 

1832 

1190 

2174 

1380 

2516 

1570 

2858 

1005 

1841 

1195 

2183 

1385 

2525 

1575 

2867 

1010 

1850 

1200 

2192 

1390 

2534 

1580 

2876 

1015 

1859 

1205 

2201 

1395 

2543 

1585 

2885 

1020 

1868 

1210 

2210 

1400 

2552 

1590 

2894 

1025 

1877 

1215 

2219 

1405 

2561 

1595 

2903 

1030 

1886 

1220 

2228 

1410 

2570 

1600 

2912 

1035 

1895 

1225 

2237 

1415 

2579 

1040 

1904 

1230 

2246 

1420 

2588 

1045 

1913 

1235 

2255 

1425 

2597 

1050     1922     1240 

2264 

1430 

2606 

.... 

1055 

1931 

1245 

2273 

1435 

2615 

1060 

1940 

1250 

2282 

1440 

2624 

1065 

1949 

1255 

2291 

1445 

2633 

1070 

1958 

1260 

2300 

1450 

2642 

lOJS 

1967 

1265  v 

2309 

1455 

2651 





1080 

1976 

1270 

2318 

1460 

2660 

1085 

1985 

1275 

2327 

1465 

2669 

1090 

1994 

1280 

2336 

1470 

2678 

1095 

2003 

1285 

2345 

1475 

2687 



1100 

2012 

1290 

2354 

1480 

2696 

1105 

2021 

1295 

2363 

1485 

2705 

.... 

1110 

2030 

1300 

2372 

1490 

2714 

.... 

.... 

1115 

2039 

1305 

2381 

1495 

2723 

1120 

2048 

1310 

2390 

1500 

2732 

1125 

2057 

1315 

2399 

1505 

2741 

1130 

2066 

1320 

2408 

1510 

2750 



1135 

2075 

1325 

2417 

1515 

2759 

1140 

2084 

1330 

2426 

1520 

2768 

1145 

2093 

1335 

2435 

1525 

2777 

1150 

2102 

1340 

2444 

1530 

2786 

1155 

2111 

1345 

2453 

1535 

2795 

1160 

2120 

1350 

2462 

1540 

2804 

.... 

1165 

2129 

1355 

2471 

1545 

2813 

.... 

1170 

2138 

1360 

2480 

1550 

2822 

1175 

2147 

1365 

2489 

1555 

2831 

1180 

2156 

1370 

2498 

1560 

2840 

1185     2165 

1375 

2507 

1565 

2849 

.... 

CENTIGRADE  AND  FAHRENHEIT  CONVERSIONS 
To  change  Centigrade  Temperatures  to  Fahrenheit  Temperatures — Add  40' 

multiply  by  1.8,  then  subtract  40°. 

To  change  Fahrenheit  Temperatures  to  Centigrade  Temperatures — Add  40' 

multiply  by  .5555  (5/9),  then  subtract  40°. 


210 


USEFUL  DATA 


MELTING  POINTS  OF  THE  CHEMICAL  ELEMENTS 


Element 

C 

F 

Element 

C 

F 

Element 

C 

F 

Helium 

>—  271 
—259 
—253? 
—223 
—218 
—210 
—188 
—169 
—140 
—101.5 
-  38.87 
—     7.3 
+  26 
30 
38 
44 
62.3 
97.5 
113.5 
S,      112.8 
S1X    119.2 

Smioe.s 

155 
186 
217-220 
231.9 
271 
302 

>—  456 
—434 
—423 
—369 
—360 
—346 
—306 
—272 
—220 
—150.7 
—  37.97 
+   18.9 
79 
86 
100 
111 
144.1 
207.5 
236.3 
235.0 
246.6 
224.2 
311 
367 
423-428 
449.4 
520 
576 

CADMIUM.  . 
LEAD  
ZINC 

320.9 
327.4 
419.4 
452 
630.0 
640 
651 
658.7 
700 
810 
810? 
>Ca<Ba? 
840? 
850 
850 
940 
958 
960.5 
1063  .  0 
1083.0 
1230 

1280 

1300-1400 

? 

1420 
1452 

609.6 
621.3 
786.9 
846 
1166.0 
1184 
1204 
1217.7 
1292 
1490 
1490 

1544'  ' 
1562 
1562 
1724 
1756 
1760.9 
1945.5 
1981.4 
2246 

2336 
$  2370- 
(  2550 

"2588" 
2646 

Cobalt  
Yttrium  
IRON  
PALLADIUM 
Chromium.  .  .  . 
Zicronium  .... 
Columbium 
(Niobium)  .  . 
Thorium  

Vanadium.  .  , 
PLATINUM 
Ytterbium.  .  .  . 
Titanium  
Uranium 

1480 
1490 
1530 
1550 
1615 
1700? 

1700? 
\      >1700 
/      <  Mo. 
1720 
1755 
? 

isoo 

<1850 
1950 
2200-2500? 
2350? 
2450? 
2550 
2700? 
2900 
3400 
>3600 

2696 
2714 
2786 
2822 
2939 
3090 

3090 
>3009 
<Mo. 
3128 
3191 

Hydrogen.  .  .  . 
Neom  
Fluorine  
Oxygen  
Nitrogen  
Argon  
Krypton  
Xenon  
Chlorine  
MERCURY.. 
Bromine  
Caesium  
Gallium  
Rubidium  .... 
Phosphorus  .  .  . 
Potassium  .... 
Sodium  
Iodine 

Tellurium.  .  .  . 
ANTIMONY. 

Magnesium.  .  . 
ALUMINUM 
Radium  
Calcium 

Lanthanum  .  .  . 
Strontium  .... 
Neodymium.  . 
Arsenic 

3272 
<3360 
3542 
4000-4500 
4260 
4440 
4620 
4890 
5250 
6152 
>6500 

Barium  
Praseodymium 
Germanium.  .  . 
SILVER  
GOLD 

Rhodium  
Boron 

Iridium  
Ruthenium  .  .  . 
Molybdenum 
Osmium  
Tantalum  .... 
TUNGSTEN  . 
Carbon...'  

Sulphur  

Indium  
Lithium  
Selenium  
TIN 

COPPER.  .  .  . 
Manganese  .  .  . 
Beryllium 
(Glucinum) 

Samarium  .... 
Scandium  .... 
Silicon  
NICKEL  

Bismuth  
Thallium 

OTHER  STANDARD  TEMPERATURES 


Substance 

Phenomenon 

C 

F 

Variation  with  pressure  (pressure  in  mm. 
of  Hg.) 

OXYGEN 

183  0 

297  4 

C°         183  0+0  01258(p        760) 

CARBON  DIOXIDE 

—  78  5 

109  3 

0.0000079(p  —  760)  2 
C°  —     78  5  |  0  01595  (p       760) 

SODIUM  SULPHATE 
Na2SO4+10H2O 
WATER  

Transformation  in- 
to anhydrous  salt 
Boiling 

32.384 
100 

90.29 
212 

•     0.  00001  ll(p—  760)  2 
C°  —  100  HO  03670(p       760) 

NAPHTHALENE  .  . 

...    do 

217  96 

424  33 

0.00002046  (p  —  760)  2 
C°  —  217  96+0  058  (p       760) 

BENZOPHENONE  
SULPHUR 

....do  
do 

305.9 
444  6 

582.6 
832  3 

C°=305  !  9  +0  .  063  (p  —  760) 
C°     411  6  f  0  0908  (p       760) 

71.9  per  cent  Ag  28  .  1  per  cent 
Cu 
SODIUM  CHLORIDE  

Eutectic  freezing  .  . 
Freezing  

779 
801 

1434 
1474 

6.000047  (p  —  760)  2 

USEFUL  DATA 


211 


C/2 


— 

0      Q 


O°K 


X 


OH 


CO 


LD 


CO 


1T3 


CD 


n 


cd 
CM 


LO 
CM 


a 


CD  <M 

3  CO 


.to 


LO 
CNJ 


^  10 


3 
5     =    I 


S2E*      cfS 


«    "    " 

t_  CO 


s 

"?       ? 


cS 


sa 


1 


LO 


LO 

c>2 

CO 

£ 

I 


'    212 


USEFUL  DATA 


AN  ACT  ESTABLISHING  A  STANDARD  GAGE  FOR  SHEET 
AND   PLATE   IRON  AND  STEEL 

Be  it  enacted  by  the  Senate  and  House  of  Representatives  of  the  United  States 
of  America  in  Congress  assembled,  That  for  the  purpose  of  securing  uniformity, 
the  following  is  established  as  the  only  standard  gage  for  sheet  and  plate  iron 
and  steel  in  the  United  States  of  America,  namely: 


Number  of 
gage 

Approximate 
thickness  in 
fractions  of 
an  inch 

Approximate 
thickness  in 
decimal  part? 
of  an  inch 

Approx- 
imate thick- 
ness in 
millimeters 

Vv  eight 
per 
square 
foot  in 
ounces 
avoirdu- 
pois 

Vv  eight 
per 
square 
foot  in 
pounds 
avoirdu    » 
pois 

Weight  per 
square 
foot  in 
kilograms 

Weight  per 
s  iuare 
meter  in 
kilograms 

Weight 
per 
square 
meter  in 
pounds 
avoirdu- 
pois 

0000000 

1-2 

.5 

12.7 

320 

20.0 

9.0 

97. 

215. 

000000 

15-32 

.46 

11.9 

300 

18.7 

8.5 

91. 

201. 

00000 

7-16 

.43 

11.1 

280 

17.5 

7.9 

85. 

188. 

0000 

13-32 

.40 

10.3 

260 

16.2 

7.3 

79. 

174. 

000 

3-8 

.375 

9.5 

240 

15 

6.8 

73. 

161. 

00 

11-321 

.343 

8.7 

220 

13.7 

6.2 

67. 

148. 

0 

5-16 

.312 

7.9 

200 

12.5 

5.6 

61. 

134. 

1 

9-32 

.281 

7.1 

180 

11.2 

5.1 

54. 

121. 

2 

17-64 

.265 

6.7 

170 

10.6 

4.8 

51. 

114. 

3 

1-4 

.25 

6.3' 

160 

10 

4.5 

48. 

107. 

4 

15-64 

.234 

5.9 

150 

9.3 

4.2 

45. 

100. 

5 

7-32 

.218 

5.5 

140 

8.7 

3.96 

42. 

94. 

6 

13-64 

.203 

5.1 

130 

8.1 

3.68 

39.6 

87. 

7 

3-16 

.187 

4.7 

120 

7.5 

3.40 

36.6 

80. 

8 

11-64 

.171 

4.3 

110 

6.8 

3.11 

33.5 

74. 

9 

5-32 

.156 

3.96 

100 

6.2  . 

2.83 

30.5 

67. 

10 

9-64 

.140 

3.57 

90 

5.6 

2.55 

27.4 

60. 

11 

1-8 

.125 

3.17 

80 

5 

2.26 

24.4 

53. 

12 

7-64 

.109 

2.77 

70 

4.3 

.98 

21.3 

47. 

13 

3-32 

.093 

2.38 

60 

3.75 

1.70 

18.3 

40. 

14 

5-64 

.078 

1.98 

50 

3.12 

.41 

15.2 

33.6 

15 

9-128 

.070 

1.78 

45 

2.81 

.27 

13.7 

30.2 

16 

1-16 

.062 

1.58 

40 

2.5 

.13 

12.2 

26.9 

17 

9-160 

.056 

1.42 

36 

2.25 

.02 

10.9 

24.2 

18 

1-20 

.05 

1.27 

32 

2 

.to 

9.7 

21.5 

19 

7-160 

.043 

1.11 

28 

1.75 

.79 

8.5 

18.8 

20 

3-80 

.0375 

.95 

24 

1.50 

.68 

7.3 

16.1 

21 

11-320 

.0343 

.87 

22 

1.37 

.62 

6.7 

14.8 

22 

1-32 

.0312 

.79 

20 

1.25 

.56 

6.1 

13.4 

23 

9-320 

.0281 

.71 

18 

1.12 

.51 

5.4 

12.1 

24 

1-40 

.025 

.63 

16 

1 

.45 

4.8 

10.7 

25 

7-320 

.0218 

.55 

14 

.87 

.396 

4.2 

9.4 

26 

3-160 

.0187 

.47 

12 

.75 

.340 

3.66 

8.0 

27 

11-640 

.0171 

.43 

11 

.68 

.311 

3.35 

7.4 

28 

1-64 

.0156 

.396 

10 

.62 

.283 

3.05 

6.7 

29 

9-640 

.0140 

.357 

9 

.56 

.255 

2.74 

6.0 

30 

1-80 

.0125 

.317 

8 

.5 

.223 

2.44 

5.3 

31 

7-640 

.0109 

.277 

7 

.43 

.198 

2.13 

4.7 

32 

13-1280 

.0101 

.257 

6H 

.40 

.184 

1.98 

4.3 

33 

3-320 

.0093 

.238 

6 

.375 

.170 

1.83 

4.0 

34 

11-1280 

.0085 

.218 

5H 

.343 

.155 

1.67 

3.70 

35 

5-640 

.0078 

.198 

5 

.312 

.141 

1.52 

3.36 

36 

9-1280 

.0070 

.178 

4M 

.281 

.12/ 

1.37 

3.03 

37 

17-2560 

.0066 

.168 

4M 

.265 

.120 

1.29 

2.87 

38 

1-160 

.0062 

.158 

4 

.25 

.1  3 

1   22 

2.69 

And  on  and  after  July  first,  eighteen  hundred  and  ninety-three,  the  same  and 
no  other  shall  be  used  in  determining  duties  and  taxes  levied  by  the  United 
States  of  America  on  sheet  and  plate  iron  and  steel.  But  this  act  shall  not  be 
construed  to  increase  duties  upon  any  articles  which  may  be  imported. 

Sec.  2.  That  the  Secretary  of  the  Treasury  is  authorized  and  required  to 
prepare  suitable  standards  in  accordance  herewith. 

Sec.  3.  That  in  the  practical  use  and  application  of  the  standard  gage  hereby 
established  a  variation  of  two  and  one-half  per  cent  either  way  may  be  allowed. 

Approved,  March  3,  1893. 


USEFUL  DATA  213 


ELECTROCHEMICAL  SERIES 

POSITION    IN    ELECTROCHEMICAL    SERIES   OF    VARIOUS 

SUBSTANCES,   IN  THE  ORDER  OF  THE   MOST 

POSITIVE  FIRST 

1  Caesium                           17  Nickel  33  Rhodium 

2  Rubidium                 v         18  Thallium  34  Platinum 

3  Potassium                        19  Indium  35  Osmium 
4lSodium                             20  Lead  36  Silicon 
S^Lithium                             21  Cadmium  37  Carbon 

6  Barium                             22  Tin  38  Boron 

7  Strontium                        23  Bismuth  39  Nitrogen 

8  Calcium                            24  Copper  40  Arsenic 

9  Magnesium                       25  Hydrogen  41  Selenium 

10  Aluminum                         26  Mercury  42  Phosphorus 

11  Chromium                       27  Silver  43  Sulphur 

12  Manganese                      28  Antimony  44  Iodine 

13  Zinc                                  29  Tellurium  45  Bromine 
14*Gallium                            30  Palladium  46  Chlorine 

15  Iron                                  31  Gold  47  Oxygen 

16  Cobalt                              32  Iridium  48  Fluorine 

All  elements  preceding  iron  are  electro-positive  to  iron.     All  following  iron  are 
electro-negative. 


214  USEFUL  DATA 


ATOMIC  WEIGHTS 

INTERNATIONAL  ATOMIC  WEIGHTS,  1918 

Symbol  Atomic  Weight 

Aluminium Al  27  . 1 

Antimony Sb  120 .2 

Argon A  39 .88 

Arsenic As  74 .96 

Barium : Ba  137 .37 

Bismuth Bi  208 .0 

Boron B  11.0 

Bromine Br  79 .92 

Cadmium Cd  112 .40 

Caesium Cs  132.81 

Calcium Ca  40 .07 

Carbon C  12 .05 

Cerium Ce  140 .25 

Chlorine Cl  35.46 

Chromium Cr  52 .0 

Cobalt Co  58 .97 

Columbium Cb  93 .1 

Copper Cu  63 .57 

Dysprosium Dy  162 .5 

Erbium Er  167.7 

Europium Eu  152 .0 

Fluorine F  19 .0 

Gadolinium Gd  157 .3 

Gallium Ga  69 .9 

Germanium Ge  72 .5 

Glucinum Gl  9.1 

Gold.... Au  197.2 

Helium He  4.0 

Holmium Ho  163 .5 

Hydrogen H  1 .008 

Indium In  114 .8 

Iodine I  126.92 

Iridium '.  .  Ir  193 . 1 

Iron Fe  55.84 

Krypton Kr  82 .92 

Lanthanum La  139 .0 

Lead Pb  207.20 

Lithium Li  6 .94 

Lutecium Lu  175 .0 

Magnesium Mg  24 .32 

Manganese Mn  54 .93 

Mercury Hg  200.6 

Molybdenum Mo  96 .0 

Neodymium Nd  144 .3 


USEFUL  DATA  215 

Symbol  Atomic  Weight 

Neon !: Ne  20.2 

Nickel Ni  58.68 

Niton  (radium  emanation) Nt  222 .4 

Nitrogen N  14.01 

Osmium Os  190 .9 

Oxygen O  16 .00 

Palladium Pd  106.7 

Phosphorus P  31 .04 

Platinum Pt  195 .2 

Potassium K  39 . 10 

Praseodymium Pr  140 .9 

Radium Ra  226 .0 

Rhodium Rh  102 .9 

Rubidium Rb  85 .45 

Ruthenium Ru  101 .7 

Samarium Sa  150 .4 

Scandium Sc  44.1 

Selenium , Se  79 .2 

Silicon Si  28.3 

Silver Ag  107.88 

Sodium : Na  23.00 

Strontium Sr  87 .63 

Sulfur S  32 .06 

Tantalum Ta  181 .5 

Tellurium Te  127 .5 

Terbium Tb  159 .2 

Thallium Tl  204.0 

Thorium Th  232 .4 

Thulium Tm  168.5 

Tin Sn  118.7 

Titanium Ti  48 . 1 

Tungsten W  184.0 

Uranium , U  238 .2 

Vanadium V  51 .0 

Xenon Xe  130.2 

Ytterbium  (Neoytterbium) Yb  173 .5 

Yttrium Yt  88 .7 

Zinc Zn  65.37 

Zirconium..  Zr  90.6 


216  INDEX 


INDEX 

Page 

Aging  Oven,  photograph  of 40 

Tests 43 

Alkali  Titration  Method  for  the  determination  of  Phosphorus 161 

Allen  Method,  determination  of  Nitrogen  in  Iron  and  Steel 151 

Alternating  Stress  Tests — Landgraf-Turner 69 

Testing  Machine,  photograph  of 68 

Aluminum  in  Iron  and  Steel,  determination  of: 

By  Bureau  of  Standards  Method 169 

By  Kichline  Method '. 75 

Armco  Ingot  Iron,  micrograph  and  analysis  of 138 

Ancient  Irons  and  Modern  Research 11 

Arsenic  in  Iron  and  Steel,  determination  of  by  Distillation  Method 77 

Atomic  Weights,  Table  of 214 

Bessemer  Steel,  micrograph  and  typical  analysis  of 144 

Billhook  of  Ancient  Origin,  photograph  and  micrograph  of 24 

Bismuthate  Method  for  the  determination  of  Manganese 139 

For  the  determination  of  Chromium 122 

Boron  in  Iron  and  Steel,  determination  of 79 

Brinell  Hardness  Test 67 

Testing  Machine,  photograph  of 62 

Brunck's  Method  for  the  determination  of  Nickel 147 

Bureau  of  Standards  Method  for  Aluminum  in  Iron  and  Steel 169 

Chromium  in  Iron  and  Steel 121 

Melting  Points  of  the  Chemical  Elements 210 

Molybdenum  in  Iron  and  Steel 145 

Silicon  in  Steel 169 

Sulphur  in  Iron  and  Steel  (Gravimetric  Method) 193 

Titanium  in  Steel 169 

Vanadium  in  Iron  and  Steel 121 

Zirconium  in  Iron  and  Steel 169 

Burrows'  Permeability  Apparatus,  photograph  of 42 

Cain  and  Maxwell  Method  for  the  determination  of: 

Carbon  in  Iron  and  Steel 101 

Cain — Electrolytic  Hydrogen  Generator  and  Reservoir 157 

Calibrating  Thermocouple,  photograph  of 52 

Cannon,  Iron  Band  from — analysis  of • 14 

Carbon  in  Iron  and  Steel,  determination  of: 

By  Cain  and  Maxwell 101 

By  Colorimetric  Method 81 

By  Combustion  Method 83 

By  Liquid  Air  Method 85 

Carbon  Monoxide  in  Iron  and  Steel,  determination  of 153 


INDEX  217 

Page 

Chemical  Analysis 73 

Elements,  melting  points  of 210 

Chisel  of  Ancient  Origin — Photograph  and  Micrograph  of 20 

Chrome-Vanadium  Steel,  determination  of  phosphorus  by  Hagmaier  Method. .  .  163 
Chromium  and  Vanadium,  determination  of,  by  Bureau  of  Standards  Method  121 
Chromium  in  Iron  and  Steel,  determination  of: 

By  Bismuthate  Method 122 

By  Demorest  Method 123 

Conductivity  and  Permeability  Tests,  photograph  of 44 

Copper  in  Iron  and  Steel,  determination  of: 

Bureau  of  Standards  Method 145 

Colorimetric  Method 125 

Iodide  Method 127 

Core  Loss  Test 37 

Corrosion,  Research  on 15 

Cushman  Method  for  the  determination  of  Spelter  Coating 179 

Data— Useful 207 

Delhi,  India,  Iron  Pillar  of — Photograph  of 8 

Delhi,  India,  Iron  Pillar — Analysis  of 9 

Demorest's  Method,  determination  of  Chromium  and  Vanadium  in  Iron  and 

Steel 123 

Dougherty's  Method,  determination  of  Vanadium  in  Iron  and  Steel 205 

Ductility  Tests— Erichsen  Method 69 

Electric  furnace,  Experimental,  photograph  of 70 

Electrical  Steels — Magnetic  Testing  of 37 

Electrochemical  Series,  Table  of 213 

Electrolytic  Resistance  Method  for  determining  Carbon 101 

Elements,  Chemical,  melting  points  of 210 

Periodic  Classification  of 211 

Epstein  Testing  Coils 38 

Erichsen  Method,  for  Ductility  Tests 69 

Etching  Methods 59 

Evolution  Method  for  the  determination  of  Sulphur  in  Iron  and  Steel 191 

Experimental  Furnace  Room 71 

Heat  Treatment 71 

Fairbank's  House,  Iron  Nails  from — Analysis  of 18 

Furnaces,  Electric,  Experimental,  photograph  of 70 

Gauge,  U.  S.  Standard  for  sheet,  plate  iron  and  steel 212 

Gravimetric  Method  (Brunck's)  for  the  determination  of  Nickel  in  Iron  and 

Steel 147 

Gravimetric  Method  for  the  determination  of  Sulphur  in  Iron  and  Steel 193 

Gravimetric  Method  for  the  determination  of  Iron  in  Iron  and  Steel 133 

Hagmaier  Method  for  the  determination  of  phosphorus  in  Chrome-Vanadium 

Steel 163 

Hardness  Tests 61 

Heat  Treatment,  Experimental 71 

Scientific 51 

Hydrochloric  Acid  Method  for  the  determination  of  Spelter  Coating 183 


218  INDEX 

Page 

Hydrogen  in  Iron  and  Steel,  determination  of 129 

Hydrogen  Electrolytic  Generator  and  Reservoir — J.  R.  Cain's 157 

Ingots,  Split 16 

International  Atomic  Weights 214 

Introduction 5 

Iron,  determination  of  in  Iron  by  Gravimetric  Method 133 

Iron  Nails  taken  from  Grave 28 

Iron — Specimens  of  Old  Iron: 

Band  from  British  Cannon 14 

Billhook 24 

Chisel 20 

From  Merrimac  Gunboat 26 

Nails,  of  Ancient  Origin 22 

Nails,  hand  forged  used  in  Mission 12 

Nails,  from  Fairbank's  House 18 

Nails,  from  Bakersfield  Weir 34 

Newburyport  Link 142 

Pillar  of  Delhi,  India 8 

Yarning  Tool 84 

Kichline  Method,  determination  of  Aluminum  in  Iron  and  Steel 75 

Landgraf-Turner — Alternating  Stress  Tests,  photograph  of 68 

Alternating  Stress  Tests 69 

Lead-Coated  Sheets,  sampling  and  analysis  of: 

Weight  of  Coating 197 

Pin  Hole  Test 165 

Magnetic  Testing 37 

Aging  Tests 43 

Core  Loss  Tests 37 

Permeability  Tests 43 

Manganese  in  Iron  and  Steel,  determination  of: 

By  Bismuthate  Method 139 

By  Color 141 

By  Persulphate  Method 137 

Test  to  determine  whether  Metal  is  Iron  or  Steel. 143 

Maxwell  and  Cain,  Bureau  of  Standards  Method  for  the  determination  of 

Carbon  in  Iron  and  Steel 101 

Melting  Points  of  the  Chemical  Elements 210 

Merrimac  Gunboat,  iron  from 26 

Metallurgical  Control 47 

Micrographs: 

American  Ingot  Iron 138 

Bessemer  Steel 144 

Billhook 24 

Chisel 20 

Nails 22 

Newburyport  Link 142 

Showing  the  effect  of  Annealing  on  hard  drawn  Wire 64 

Of  Steel — Properly  and  Improperly  Annealed 54 

Microscopic  Tests 57 


INDEX  219 

Page 

Microscope,  view  of  Apparatus 56 

Molybdenum  in  Steel,  determination  of,  Bureau  of  Standards  Method 145 

Nails,  analysis  of: 

Iron  Nails  of  Ancient  Origin 22 

From  Bakersfield  Weir 34 

From  Fairbank's  House 18 

Hand  Forged  Nail  used  in  Mission 12 

Newburyport  Link: 

Analysis  of 142 

Micrograph  of 142 

Nickel  in  Iron  and  Steel,  determination  of: 

Brunck's  Gravimetric  Method 147 

Titration  Method 149 

Nitrogen  in  Iron  and  Steel,  determination  of 151 

Optical  Pyrometers 55 

Oxidation  Method  for  the  determination  of  Sulphur  in  Iron  and  Steel 195 

Oxygen  in  Iron  and  Steel,  determination  of 153 

Permeability  Apparatus,  Burrows — photograph  of 42 

Permeability  and  Conductivity  Tests — photograph  of 44 

Permeability  Tests — Electrical  Steels 43 

Periodic  Classification  of  the  Elements 211 

Persulphate  Method  for  the  determination  of  Manganese  in  Iron  and  Steel.  .  . .  137 
Phosphorus  in  Iron  and  Steel,  determination  of: 

Alkali  Titration  Method 161 

Determination  of  in  Chrome- Vanadium  Steel 163 

Physical  Tests 67 

Physical  Testing  Section,  photograph  of 60 

Pin  Hole  Test — Lead  Coated — Tin  and  Terne  Plate 165 

Polishing  Equipment,  photograph  of 58 

Polishing  Methods 59 

Pyrometry — Optical  and  Thermoelectric '. 55 

Recording  Potentiometer,  photograph  of 50 

Research  on  Corrosion 15 

Scientific  Heat  Treatment 51 

Section  through  Split  Ingots 16 

Sheet  Gauge— U.  S.  Standard  for  Sheets,  Plate  Iron  and  Steel 212 

Silicon  in  Iron  and  Steel,  determination  of 167 

Silicon  in  Steel,  determination  of,  Bureau  of  Standards 169 

Spelter  Coating,  determination  of  on  sheets  and  wire 183 

Cushman  Method 179 

Lead  Acetate  Method 189 

Spikes,  Failure  of  Steel,  photograph  and  analysis  of 32 

Steel  Pipe  Failure,  photograph  and  analysis  of 30 

Sulphur  in  Iron  and  Steel,  determination  of 191 

Bureau  of  Standards   Method 193 

Evolution  Method 191 

Gravimetric  Method 193 

Oxidation  Method..                                                                                    .  195 


220  INDEX 

Page 

Table  of  Electrochemical  Series 213 

Atomic  Weights 214 

Conversion  of  Fahrenheit  and  Centigrade  Temperatures 208 

Melting  Points  of  the  Chemical  Elements 210 

U.  S.  Standard  Gauge  for  Sheet  Metal 212 

Tensile  Tests 67 

Terne  Plate — Analysis  of — Weight  of  Coating 197 

Pin  Hole  Test 165 

Testing  Coils,  Epstein  Core  Loss  Tests,  photograph  of 38 

Thermocouples,  Calibrating — photograph  of 52 

Thermoelectric  Pyrometers 55 

Tin  Plate — Analysis  of — Weight  of  Coating 197 

Pin  Hole  Test 165 

Titanium  in  Steel,  determination  of: 

Bureau  of  Standards  Method 169-203 

Titration  Method  for  the  determination  of  Nickel 149 

Useful  Data . . 207 

Vanadium  in  Iron  and  Steel,  determination  of: 

Bureau  of  Standards  Method 121 

Demorest's  Method 123 

Dougherty's  Method 205 

Weights— Atomic,  Table  of 214 

Wire,  Hard  Drawn  and  Annealed,  micrographs  of 64 

Yarning  Tool — photograph  and  analysis  of 84 

Yensen,  T.  D.,  determination  of  Carbon  in  Iron 85 

Zirconium — determination  of — Bureau  of  Standards  Method  .                       169 


- 


THIS  BOOK  IS  DUE  ON  THE  LAST  DATE 
STAMPED  BELOW 


AN     INITIAL    FINE     OF    25     CENTS 

WILL  BE  ASSESSED  FOR  FAILURE  TO  RETURN 
THIS  BOOK  ON  THE  DATE  DUE.  THE  PENALTY 
WILL  INCREASE  TO  SO  CENTS  ON  THE  FOURTH 
DAY  AND  TO  $I.OO  ON  THE  SEVENTH  DAY 
OVERDUE. 


3  25  1933 
APR   261933 
NOV  161933 


REC-D  LD 
MAY  1 8 1951 

3Fflb'58HJ| 
REC'D  LD 
JAN  19 


LD  21-50m-l,'33 


UNIVERSITY  OF  CALIFORNIA  LIBRARY 


